Chapter 1

Arbitrage, Mobility, and Equilibrium Prices

Abstract

This chapter explores the implications of a world in which economic agents maximize profits and their economic well-being, where goods and services and factors of production are free to move across national borders without facing any impediment or “transportation costs.” The analysis focuses on the market clearing process, which leads to the identification of global and national equilibrium prices. Then the analysis is extended to include transportation costs, different degrees of factor mobility effects on the equilibrium, the relative prices between two commodities, and the terms of trade between two economies. The process yields several insights, which we use to examine the impact or incidence of alternative policies on the economy and the effect of restrictions in the movement of goods or factors of production and whether these policies in fact produce the results that the pundits and policymakers expect? The analysis also allows us to identify the policies that, in the context of our framework, will deliver the desired objectives and those who would not.

Keywords

purchasing power parity
PPP
law of one price
terms of trade
real exchange rate
interest rate parity
IRP
Fisher equation
factor price equalization
Social scientists and money managers value parsimony, forecasting accuracy, and explanatory power. As a result, these scientists aim to develop the simplest models and theories possible with the maximum predictive and/or explanatory power possible. The idea behind the modeling assumption is to eliminate and/or remove superfluous details and focus on the issues that are truly important to the topic at hand. They try to maximize their bang for the buck. Given the forecasting accuracy and explanatory power, the simplest theories are considered the most elegant. They are also easier to articulate and in general make the most sense. They are also the easier sale; they make a good story and may even deliver performance.
The simplification of the modeling is not without risk. In some cases once the simplifying assumptions regarding the world are made, the die is cast. In these cases, the policy implications are a direct result of the assumptions made by the model builder. Viewed this way, one can consider economic modeling an art, the art of choosing the relevant set of simplifying assumptions. One example we have frequently used is the combined assumptions of profit maximization and free mobility of goods and services/factors of production. These apparently innocuous assumptions lead to a very strong implication: Differences in prices across national borders will be arbitraged away and so will the differences in rates of returns across countries.
The equalization of factor returns across national borders is insured by the mobility of factors of production. However, Nobel Prize winner Paul Samuelson also showed that if there are enough goods and services traded across national boundaries, the returns to the factors of production could be equalized, even when the factors of production do not move across national borders [1]. This is an important point, for it suggests that a combination of goods and factor mobility insures the equalization of returns to factors that are immobile across national borders [2]. An example will clear this point. If labor and land are used to produce rice, which is freely traded, we know that the price of rice will be equalized across national borders, say $100 per bushel. If labor is free to move, the wages will also be equalized across borders. If both countries use the same techniques, then the labor costs will be the same across the economies, say $40. Given the total coast and labor costs, it follows that, with the same technology, the land intensity will be the same and so will the land returns, $60 in this example. The assumption of free trade, zero transportation costs, and the same technology lead to the result that the production labor costs are the same across the national borders. Under these conditions the returns to the landowners will be the same across the two economies.
In the area of international finance these key simplifying assumptions yield the result commonly known as purchasing power parity (PPP). Put another way, profit maximization and free mobility insure that the dollar price of any commodity will be the same across the world. The origin of this literature can be traced to Swedish Economist Gustav Cassel believed that, if an exchange rate was not at parity, it was in disequilibrium—either prices or the exchange rate would adjust until parity was again achieved. Parity would be ensured by arbitrage [3].
The remaining chapters develop a simple approach with a dual purpose: one is to identify the economy’s adjustment process to shocks or economic disturbances and the other purpose is to analyze and suggest policies that will address some of the problems faced by the domestic and global economies.
We begin by making the simplest set of assumptions and see how far we can take these assumptions. After exploring and developing the insights derived, we introduce additional assumptions and examine how the additional add to the ability of our framework to explain and analyze additional economic events of greater complexity. As we acquire new insights, we become better equipped to develop policies aimed at addressing the economic problems at hand.
The astute investor will be able to use the framework developed here to anticipate the adjustment process needed to achieve national and global equilibrium resulting from policy changes and/or unexpected economic shocks. In some cases, these insights may be translated into new portfolio and/or investment strategies, which we have called the value timing approach [4]. The approach is similar to that of the peeling an onion: at each successive layer, the richness and intricacies of the framework will be revealed. Let’s begin by exploring the implications generated by the assumptions of perfect mobility and profit maximization.

A 2X2X2X2 World

Initially we assume that there the world consists of:
  1. 1. Two countries: Westland and Lakeland.
  2. 2. Two goods: Westland produces mostly wine and Lakeland produces mostly cheese. Pwn and Pcn denote the price in Westland of wine and cheese in notes currency. Pwp and Pcp denote the price in Lakeland of wine and cheese in pesos currency.
  3. 3. Two factors of production: Labor and land.
  4. 4. Two currencies: Westland uses notes as its currency and Lakeland uses the peso as its currency.
The rationale for the 2X2X2X2 assumptions is due to the fact that we live in a three dimensional world. And one can draw two variables in a page or blackboard and analyze the effect of two variables, say labor and land on the level of production of one or two particular goods. Prior to the advent of high powered mathematics, economists were quite fond of graphical analysis and intuitive solutions. Intricate knowledge of the two-sector model was a must for those economists aspiring to understand international trade and its general equilibrium conditions. Harry Johnson’s used the two-sector model not only in his lectures, but also in many of his most brilliant pieces is a testimony to the versatility of the two-sector model and its applicability to many economic problems and policy issues [5].

Equilibrium Under Autarky

Initially we assume that Lakeland and Westland do not trade with each other. Under this assumption the local price of cheese and wine is determined solely by local demand and supply conditions. Fig. 1.1A depicts the autarkic equilibrium for the cheese market in Lakeland. The market clearing conditions are determined solely by the intersection of the demand for cheese, DL, and supply of cheese, SL, in Lakeland.
image
Figure 1.1 (A) Lakeland autarkic equilibrium for the cheese market. (B) Westland autarkic equilibrium for the cheese market.
The point of intersection of the demand and supply curves (DL and SL) is the market “clearing” equilibrium price for cheese, Pcp*image, and quantity of cheese, Qcl*image, produced in Lakeland absent in the international trade.
Similarly, Fig. 1.1B shows the demand (Dw) and supply (Sw) conditions for cheese in the Westland economy. The intersection of the two curves denotes the market clearing price, Pcn*image, and quantity of cheese produced, Qcw*image, in Westland under the autarkic conditions.

Global and National Equilibrium

Next, we explore the implications of opening trade between the two nations under the following assumptions regarding profit maximization and mobility:
  1. 1. We assume that the economic agents maximize profits.
  2. 2. We assume that there are no transaction costs or any frictions restricting the mobility of goods and services across the two economies.
These two assumptions are sufficient to ensure that the profit maximizing agents “arbitrage” any differences in prices across national borders. More than likely the autarky cheese price, the market clearing price that would prevail in the absence of trade will be different in the two localities. In the example depicted in Fig. 1.1, they are, here is how the arbitrage process would work: in the absence of trade between the two countries, Pcp*image and Pcn*image denote the autarky market clearing price of cheese in Lakeland and in Westland.
The autarky (no trade) price in Lakeland is given in pesos, while the corresponding price in Westland is quoted in notes (the Westland currency). Fig. 1.2 shows the autarky prices of cheese for both countries in pesos, the Lakeland currency. In order to compare the two prices it is necessary to convert the two prices to a common currency.
image
Figure 1.2 Arbitrage (A) country 1: Lakeland (peso), (B) country 2: Westland (in Pesos), (C) world equilibrium.
Initially, in the absence of trade the price is higher in Westland than it is in Lakeland. That creates a profit opportunity that can be arbitraged away by profit maximizing agents
That is,

E×Pcn*>Pcp*

image(1.1)
The difference in price may be attributable to several factors. One possibility is differences in tastes. Other possibilities are the differences in technology or production function and or relative factor endowments. In what follows we will assume that the two economies have similar tastes as well as similar technologies. As trade opens between the two economies, cheese will be exported from the locality with the lower price of cheese, Lakeland, into the higher price locality, Westland in this case. Initially, the arbitrageurs will make a profit equal to the difference in the two prices:

Arbitrage profits per unit=E×Pcn*Pcp*

image(1.2)
As a result of the arbitrage process, there will be a smaller supply of cheese in the exporting locality, which will, all else being the same, drive the price up. At the same time there will be a higher supply of cheese in the importing country, which will, all else being the same, reduce the price of the cheese in the importing country.
Notice that we appear to be quite fond of using and numbering equations. There is a rationale behind it. We use the equations to memorialize the different relationships and assumptions, as well as a filing system for these relationships so that we can refer to it later on when we expend and or modify the relationships describing our basic framework.
The combined effect of these arbitrage driven price changes ultimately leads to the following responses:
  1. 1. After the opening of trade, the higher price per pound of cheese in Westland produce a profit opportunity for the people of Lakeland. In order to take advantage of the higher price in Westland, Lakeland’s producers increase their production in order to export to Westland and take advantage of the higher prices. This is depicted in Fig. 1.2 as an upward movement along Lakeland’s supply curve. The production of cheese will rise from Qcl*image to Scl.
  2. 2. The higher price of cheese in Westland will also affect the Lakeland cheese consumers. As the market price will rise their consumption of cheese will decline. This is depicted in Fig. 1.2 as an upward movement along the demand curve. The local consumption of cheese in Lakeland will fall to Qcl from Qcl*image.
  3. 3. The increased production less the reduced consumption in Lakeland leads to a surplus of cheese that is now exported to Westland. Lakeland exports are denoted by Xcl.
  4. 4. The lower price for a pound of cheese in Lakeland will produce a profit opportunity for the people of Westland too. In order to take advantage of the lower price, arbitrageurs will import cheese from Lakeland and sell in Westland at a price higher than Lakeland but lower than Westland. The lower price will result in an increase in the quantity demanded of cheese. This is depicted in Fig. 1.2 as a downward movement along Westland’s demand curve for cheese. Westland demand for cheese will increase from Qcw*image to Qcw. The import competition also puts downward pressure on the price of and production of cheese in Westland. This is depicted in Fig. 1.2 as a downward movement along the supply curve, the production of cheese in Westland will fall to Scw from Qcw*image.
  5. 5. Westland cheese imports, Mcw, will be the difference between the domestic consumption of cheese and the domestic production of cheese in Westland, that is, ScwQcw.
The arbitrage process continues as long as there is a cheese price differential between the two countries. The process stops when cheese prices are equalized across the two localities. At that point there is no longer an arbitrage profit opportunity.
Global equilibrium is depicted in Fig. 1.2 as the intersection of the world demand and supply curve for cheese. The global demand is nothing more than the sum of the two countries demand curves while the global supply is the sum of the two countries supply curves for cheese. The global market clearing prices and quantities of cheese produced can be depicted as Pceimage and Qceimage.
Once the global market clearing conditions are established, that is, the world prices are determined, then it is possible to use the global price combined with the local demand for and supply of a commodity such as cheese in each economy, and determine the consumption and production of cheese and thus the net exports in each country.
Namely:

Xcl=SclQcl

image(1.3)

Mcw=QcwScw

image(1.4)
Where Scl and Scw denote the production of cheese in Lakeland and Westland, respectively, and Qcl and Qcw denote the consumption of Cheese in Lakeland and Westland, respectively. The two-country world model is fairly general. When focusing on one particular country, it may be possible to lump or aggregate all other countries into “the rest of the world” or country 2.
The Law of One Price: The insight gained here is that profit maximization combined with absence of transaction costs ensures that economic agents will cause the cheese prices in notes in Westland multiplied by the exchange rate, Pcn*E, to be the same as the peso price of cheese in Lakeland. Xcl
Formally:

Pcp=Pcn×E

image(1.5)
Similarly, arbitrage ensures that the peso price of wine in Westland, Pwn × E, is the same as the peso price of wine in Lakeland, Pwp. That is,

Pwp=Pwn×E

image(1.6)
E is the exchange rate between the two currencies. As we have shown earlier it allows converting the prices in terms of one country’s currency into prices expressed in another country’s currency. That is, how many pesos versus how many notes are needed to purchase a bottle of wine or a pound of cheese. The exchange rate is defined as the ratio of the price of a commodity; say cheese, in the two currencies. Eqs. (1.5) and (1.6) show that arbitrage insures that the price of any commodity expressed in one currency is the same all over the world.
Eqs. (1.5) and (1.6) show that PPP holds across commodities, this implies that there is a single global price for each of the commodities. Fig. 1.2 illustrates graphically the global equilibrium. The world demand for and supply curves are nothing more than the sum of the demand for and supply of cheese for each of the countries in the world.
If the relative price remains unchanged, then wine and cheese tend to be consumed in fixed proportions. If that is generally the case for all goods consumed, then one can make a composite good comprising all the goods and services consumed by each economy, and call it the economy’s consumer price index (CPI) [6].
Under the assumption that the terms of trade remain unchanged, assuming similar consumer baskets among the economies, arbitrage will ensure that the “LAW OF ONE PRICE” prevails. That is, the peso price of the consumer basket will be the same in each locality.
In a formal equation, the law of one price or PPP relationship can be expressed as:

CPIp=CPIn×E

image(1.7)
The dynamic version of this equation can be expressed in terms of the rate of change of each CPI, that is, the domestic inflation rate in local currency, and the rate of change of the exchange rate:

πp=πn+є

image(1.8)
Where πp, denotes the Lakeland inflation rate in pesos; πn, the Westland inflation rate in notes; and є, is the exchange rate appreciation of notes in terms of pesos.
Eq. (1.8) is nothing more than the dynamic version of the PPP equation also known as the law of one price. It is easily derived by differentiating logarithmically Eq. (1.7). It shows that when relative prices are constant, the inflation rate of the country with the appreciating currency is lower than the other currency by the amount of the exchange rate appreciation. Put another way, differences between the inflation rates of the two countries are directly and exactly reflected on the rate of change in the currency exchange rate.

Global Equilibrium and the Trade Accounts

The assumption of a two-country world allows us to establish several identities and equalities. For example, since there are only two countries in this world, Fig. 1.2 shows that equilibrium requires that the global demand equal global supply. Therefore one country’s cheese imports have to match the other country’s cheese exports.
That is,

Xcl=Mcw

image(1.9)
Where Xcl denotes Lakeland’s cheese exports and Mcw denotes Westland’s cheese imports.
The same logic applies to the wine. The one difference being that Westland is the low cost producer under autarky and hence the exporter.

Xww=Mwl

image(1.10)
Xww denotes Westland wine exports and Mwl denotes Lakeland wine imports.
But that is not all. In this world there is only one time period, profit and utility maximization implies that there will be no net lending among the parties. The reason is simple: in a one period model, the lending never gets repaid; hence the consumers would be better off not lending and increasing their consumption and thus their utility or well-being. Lending or borrowing requires multiperiod modeling. Lending affords the lender the opportunity to transfer resources into future time periods, presumably to finance future consumption. For now we will ignore the multiperiod issues.
So far we have established that in a single period model, utility maximization yields the following budget constraint: income will equal expenditures at all times. That is,

Yi=Pci×Sci+Pwi×Swi

image(1.11)
Where Yi denotes the income of country i measured in its local currency.

Ci=Pci×Cci+Pwi×Cwi

image(1.12)
Where Ci denotes the i country’s overall consumption of wine and cheese measured in local currency.
Subtracting the domestic consumption from both the income and expenditures yields the result that for each country the value of the imports must equal the value of the exports. After some manipulations we can easily show that if one country imports a commodity it must finance the imports of each country yields the result that the world trade balance in the trade balance for each country, TB, will always be zero. That is,

TBl=Pwp×MwlPcp×Xcl=0

image(1.13)
Where Pwp, denotes the price of wine in pesos (Lakeland’s currency); Mwl, Lakeland wine imports; Pcp, the price of cheese in pesos; and Xcl, is Lakeland’s exports of cheese.

TBw=Pcn×McwPwn×Xww=0

image(1.14)
Where Pwn, denotes the price of wine in notes (Westland’s currency); Xww, is Westland’s wine exports; Pcn, is the price of cheese in notes; and Mcw, is Westland’s exports of cheese.
Irrespective of which currency is used, the value of Lakeland cheese exports will equal the value of Lakeland wine imports. The budget constraint also means that the value of Westland exports equals the value of Westland imports.

Pwp×Mwl=Pcp×Xcl=Pcn×E×Mcw=Pwn×E×Xww

image(1.15)

The Terms of Trade or Real Exchange Rate

Arbitrage also ensures that the relative price, terms of trade, or real exchange rate is the same across the two markets. That is, one pound of cheese gets the same amount of wine in Lakeland or Westland, otherwise an arbitrage profit opportunity would continue to exist. And this brings us to the second term we need to define. The terms of trade T, between the two economies. It is a measure of the relative price of wine in terms of cheese. T, measures how many units of one of the goods are needed to acquire a unit of the other good. That is, how many pounds of cheese are needed to acquire a bottle of wine Therefore the arbitrage process also ensures that the relative price of the two goods in question are equalized across economies:

T=Pwn/Pcn=Pwp/Pcp

image(1.16)

Interest Rate Parity

Nominal interest rates, iw and il, denote the opportunity costs of holding noninterest bearing money in terms of bonds in Westland and Lakeland currencies, respectively. Borrowers and lenders have the choice of either borrowing or lending in either of the two currencies (notes or pesos).
Let’s take the perspective of the people of Lakeland.
  • If they save 1 peso at home at the end of the year, they receive 1 + ip, or 1 peso plus the Lakeland/peso interest rate.
  • Alternatively, the investor could have converted the peso into notes at the current spot exchange rate, invested in notes in Westland’s market and earn 1 + in at the end of the year, while simultaneously buying a futures contract on the currency that locks in the conversion or exchange rate. Investors would then arbitrage any difference between the two strategies, investing in the home market or foreign market. The end result of the arbitrage is what is called the interest rate parity theorem [7]:

ipin=є

image(1.17)
Next, we need to add one more relationship, the Fisher equation, relating the nominal and real interest rates (ρ) and the inflation rates (π) [8]

ip=πp+ρp

image(1.18)

in=πn+ρn

image(1.19)
The interpretation of the equation is straight forward: the inflation rate denotes the opportunity costs of holding cash in terms of goods and services in each of the economies. That is, those who hold commodities experience a nominal capital gain equal to the inflation rate. The real rate of return is nothing more than the interest rate charged for lending and borrowing in terms of the commodity in question. For example, if one borrows 100 bottles of wine to repay them a year later and the borrower has to repay 103 bottles, the real interest rate in terms of wine, ρn, is 3%. Similarly, if one borrows 100 pounds of cheese and has to repay 104 pounds of cheese a year later, the real interest rate in terms of cheese, ρp, is 4%.
The Fisher equation is now easily described. If a person borrows 100 pounds of cheese, in order to break even, they have to produce 104 pounds of cheese. If the inflation rate is 3%, then at the end of the year the lender receives 4% more cheese, as well as a 3% appreciation of the value of the cheese in peso prices, for a nominal rate of return in pesos of 7%.
If one subtracts Eq. (1.18) from Eq. (1.19), one ends up with

ipin=πpπn+(ρpρn)

image(1.20)
Now if one substitutes Eq. (1.17) in Eq. (1.20), we get the following conclusion:

ρl=ρw

image(1.21)
The intuitive explanation for this result is straightforward. If the relative prices between wine and cheese remain unchanged, the borrowers and lenders will be indifferent as to how individuals transfer resources to the future from the present. This is a very important result for it shows that the conditions under which interest rate parity and PPP hold result in the complete equalization of real rate of returns across economies.
One implication of this analysis is that whether you invest abroad or at home, the real rate of return is the same. There is no need to go anywhere else in the world. Another insight is that the adoption of free trade and the elimination of trade barriers leads to a convergence of rates of returns. The implementation and adoption of the Euro is a good case study of the convergence proposition [9].

What Happens When the Terms of Trade Change in Predictable Directions?

The terms of trade, T, is defined as the price of one country’s exports in terms of the other (say the price of wine in terms of cheese). A change in the terms of trade means that for the economy with the more favorable terms of trade, say Lakeland, a pound of cheese is now able to get a larger quantity of wine. This means that the rate of return earned by producing cheese increases relative to the rate of return earned in the production of wine. As a result Eq. (1.21) has to be modified to account for the change in terms of trade. In dynamic form the terms of trade equation now becomes:

ρl=ρw+τ

image(1.22)
Where τ denotes the change in terms of trade between the two economies.
The combining of Eqs. (1.17) and (1.20), yields the following relationships:

iliw=є=πlπw+(ρlρw)

image
Substituting Eq. (1.22) into the previous equation yields:

i1iw=є=π1πw+τ

image
Rearranging the terms we get an expression for the changes in terms of trade:

τ=є(πlπw)

image(1.23)
This equation provides an interesting insight: violations of PPP reflect changes in the terms of trade of an economy.
The change in the terms of trade is measured as an appreciation of the exchange rate over and above the inflation rate differential between the two currencies. It reflects an increase in the real rate of return of an economy relative to the real rate of return of the other economy.
The Real Exchange Rate or Terms of Trade Appreciation has a Secondary Effect on the Economy: The higher real rate of return means that one pound of cheese in the earlier example can now buy more bottles of wine. This induces people in Lakeland to devote more resources to cheese production at the expense of wine production. These forces will also be at work in Westland, where resources will now be diverted from wine production to the production of the import substitution good: domestic cheese. Therefore, cheese production worldwide increases, while wine production unambiguously declines.
The higher rate of return also means that the resources that are intensive in the production of the appreciating good, say pasture land, experiences an increase in valuation, while the factors intensive in the production of wine decline in value [10]. Cheese land appreciates relative to wine land. Given the assumption that Lakeland is intensive in cheese land relative to Westland, we expect to see the Lakeland stock market outperform the Westland stock market.
The Terms of Trade Analysis is Simple and Straightforward: When a commodity’s relative prices remain unchanged, for example, when the price of cheese in terms of wine remains unchanged, so do the terms of trade. In that case, arbitrage ensures that PPP, holds and real rates of return are equalized across countries. Under PPP, the exchange rate changes only reflect inflation rate differentials across countries.
Now if PPP does not hold, then the deviations from PPP reflect relative price changes. For example, when the price of cheese in terms of wine increases, that is, terms of trade changes, the country which experiences currency appreciation over and above the inflation rate differential, Lakeland, will also experience a stock market appreciation relative to its trading partner, Westland.
The increase in real rate of return diverts capital from wine production to cheese production in both countries, Lakeland and Westland. Therefore global production and employment in the cheese industry will increase, while wine production and employment in the wine industry decreases.

Adding the Final X2

Recall that we have assumed a 2X2X2X2, so far we have introduced the two countries, two goods, and two currencies. However we are still short of a 2. We now address this deficiency by introducing two factors of production.
In what follows, both factors are considered in the production of the two goods, wine and cheese, in both countries. However they are used in different proportions, we will call one factor “wine intensive” while the other will be called “cheese intensive.”
Assuming that both countries have the same technology and tastes across the two economies, it is easy to show and/or argue that the relative abundance of the factors of production is a major determinant of the relative production of wine and cheese. In that case it is easy to conclude that in Westland the wine intensive factor will be relatively abundant while the cheese intensive factor will be relatively abundant in Lakeland.
Under some general conditions one can show that there is a one to one correspondence between the relative prices of the final product, that is, wine and cheese, and the returns from the two factors in question [11].
In order to show this lets specify the general model and then show what assumptions are required to make the conclusions that we are referring to in the previous paragraphs:

Pwl=αl×Wwl+(1αl)×Rwl

image(1.24)
Pwl, denotes the cost of producing a bottle of wine in Lakeland in pesos; αl, represents the labor share of the costs; Wwl, the prevailing wage in Lakeland wine sector; Rwl, is the rental cost of wine land in Lakeland.

Pcl=βl×Wcl+(1βl)×Rcl

image(1.25)
Pcl, denotes the cost of producing a pound of cheese in Lakeland in pesos; βl, represents the labor share of the costs; Wcl, the prevailing wage in Lakeland cheese sector, Rwl, is the rental cost of cheese/dairy land in Lakeland.

Pww=αw×Www+(1αw)×Rww

image(1.26)
Pww, denotes the cost of producing a bottle of wine in Westland in notes; αl, represents the labor share of the costs; Www, the prevailing wage in Westland wine sector; Rwl, is the rental cost of wine land in Westland.

Pcw=βw×Wcw+(1βw)×Rcw

image(1.27)
Pcw, denotes the cost of producing a pound of cheese in Westland in notes; βl, represents the labor share of the costs; Wcw, the prevailing wage in Westland cheese sector; Rww, is the rental cost of cheese/dairy land in Westland.
The previous four equations contain four different prices, four wage rates, and four rental rates for the land. That is, 12 unknown in 4 equations. Assuming that the equations are independent, we will need to remove eight degrees of freedom in order to obtain a unique solution to the system of equations. There are some reasonable assumptions that we can make and depending on these assumptions we will get different answers regarding the impact of demand and supply shocks on the different prices and or factor returns.
Scenario 1: Free trade in goods and services.
So far we have been assuming that there is free trade between the two economies, Lakeland and Westland, and that there are no transportation costs. These two assumptions combined with arbitrage yield the result that the peso price of cheese is the same anywhere in the world and that the peso price of wine is also the same everywhere in the world. That is,

Pwl=E×Pww

image(1.28)
and

Pcl=E×Pcw

image(1.29)
Our analysis also has been assuming that there is no migration across national borders. That is, the factors of production are immobile across borders. However we have implicitly assumed that they are mobile within national borders. That is labor and land production can shift costless from cheese production to wine production and vice versa. These assumptions mean that arbitrage leads to the equalization of wage rates across sectors within each of the economies and of the rental price of land. Under these assumptions the following relationships must hold at all times:

Wwl=Wcl

image(1.30)

Www=Wcw

image(1.31)

Rwl=Rcl

image(1.32)
and

Rww=Rcw

image(1.33)
Assuming that both countries have the same technology, substituting Eqs. (1.28) through (1.33) into Eqs. (1.24) to (1.27) yields:

Pwl=α×Wl+(1α)×Rl

image(1.34)

Pcl=β×Wl+(1β)×Rl

image(1.35)
and the difference between the two prices

PclPwl=(βα)×(WlRl)

image(1.36)
or

WlRl=(PclPwl)/(βα)

image(1.37)
If one takes the price of the finished products as given, the previous two equations has two unknowns and can be solved for the prevailing wage rate and rental rate in Lakeland, that is, in pesos:

Rl=(β×Pwlα×Pcl)/(αβ)

image(1.38)
and

Wl=((1β)×Pwl(1α)*Pcl)/(αβ)

image(1.39)
The information presented in the previous section shows that under the free trade assumption and no transportation costs prior to the opening of trade, a pound of cheese was relatively cheaper in Lakeland than in Westland (Fig. 1.2). From Lakeland’s perspective, the opening of trade resulted in an increase in the price of cheese in Lakeland and a decline in the price of cheese in Westland. It is therefore safe to conclude that:
  • The returns to the cheese intensive factors in the production of cheese in Lakeland rises, while those in Westland declines. If Cheese is the relatively labor intensive factor, then β > α holds at all times and we can safely conclude that in Lakeland, the return to the cheese intensive factor, labor, rises both in absolute terms, Eq. (1.36), as well a rising relative to the Wine intensive factor, see Eq. (1.37). In Westland, the cheese intensive factor experience an absolute and relative decline.
  • The same information also suggests that the returns to the factor intensive in the production of wine rises in absolute and relative terms in Westland while declining in both absolute and relative terms in Lakeland.
This analysis is very important because it allows us to identify the changes in factor returns due to changes in the terms of trade. As we will show later on, this is key component of the protectionist pressures and the politics of the special interest groups.
A different scenario: All factors of production are free to move across borders but the goods are not permitted to move.
Under these assumptions we know that if labor is free to move across sectors, the wage rate differential is arbitraged. We know that land is not mobile. For the purposes of this section we will assume that capital is the second factor used in the production of both wine and cheese.
The mobility of the factors of production combined with profit maximization yields the following equilibrium conditions:

Wcl=Wwl=E×Wcw=E×Www=W

image(1.40)
and

Rcl=Rwl=E×Rcw=E×Rww=R

image(1.41)
In an integrated world, measured in a common currency, the wage rate or rental rate of a factor return is the same everywhere in the world. Hence

Pcl=E×Pcw

image(1.42)
and

Pwl=E×Pww

image(1.43)
Profit maximization insures that migration and movement would continue until the factor returns were equalized across countries. If the technologies are the same across the economies, the equalization of factor returns implies that the price of the final products will also be equalized across the two economies. The conclusion being that as far as the product and factor price is concerned migration is a substitute for trade, a very important insight that we can use later on.
A Third Scenario: Not all goods and or factors are mobile. The profit maximization assumption means that, absent transportation costs, arbitrage can be affected through either trade in goods, production factor migration, and or a combination of the two. In practice the arbitrage is also shaped by transaction and/or transportation costs incurred by the products in addition to the factors of production.
The profit maximization assumption ensures that the arbitrage process will be one that minimizes the transaction and/or transportation costs, as broadly defined. In general it may make sense to argue that some of the factors of production face higher transportation costs than the goods in question. Land is one such example; it is virtually impossible to move land from one country to another. People may be attached to their family and localities and may not choose to migrate in spite of a salary differential. Hence some factors of production and some goods may face higher “transportation costs” than the cost of shipping wine and/or cheese. Given that we know:
  • Free trade in the two finished goods leads to equalizations of the two factor returns even if the factors of production do not move across national borders.
  • Free mobility of the two factors of production leads to equalization of the two factor returns as well as the equalization of the price of the two finished goods even if the finished goods do not move across national borders.
However, we have yet to address the issue of what happens when only some goods and some factors are free to move across national borders. What is a necessary condition for the equalization of factor and product prices across the national borders? We hope to answer the question in the next few paragraphs.
Let’s assume that one of the goods faces no transportation or any other costs when moving across national borders. In that case arbitrage insures that the price of a bottle of wine is the same in the two countries. That is,

Pwl=E×Pww

image(1.44)
We also assume that one of the factors of production is able to move freely across national borders as well as within the country. The mobile labor arbitrages any differences in wages in the different sector and countries by moving from the low wage areas to the higher wage areas until there is no gain from moving.

Wcl=Wwl=E×Wcw=E×Www=W

image(1.45)
Although the other factor, land, cannot move across national borders, it can be used to produce either wine or cheese. This means that the rates of returns of the immobile factor will be equalized across sectors within the countries.

Rc1=Rwl

image(1.46)
and

E×Rcw=E×Rww

image(1.47)
Arbitrage requires that

Pwl=E×Pww

image
Substituting these equations into (1.24) and (1.26), we get:

α×W+(1α)×Rwl=α*W+(1α)×Rww×E

image(1.48)
The previous equation yields the following result:

Rwl=Rww×E

image(1.49)
Which, in turn, yields:

Rcl=Rwl=E×Rcw=E×Rww=R

image(1.50)
The mobility of one product and one factor of production lead to the equalization of the immobile factor, as well as the return of the immobile factor across national borders.

Mobility, Trade, and the Equalization of Price and Factor Returns Across Borders

Each of the three scenarios presented leads to the equalization of factor returns and product prices across national borders. By combining these three scenarios it leads to a generalization of the conditions that lead to the equalization of factor prices and factor returns across national borders. It suggests that a necessary condition is that the sum of mobile goods and or factors has to equal or be greater than the number of immobile goods and factors within the country.
Several implications are easily derived from our framework and lead to a few interesting insights. Under the assumptions made, arbitrage ensures that there is a single price for each of the commodities in the global economy. This is the so-called “Law of One Price.”
A related insight is that the global economy is an integrated economy with a single global market for each of the commodities. This is very important, for it suggests that changes in global prices elicit the same qualitative response across the global economy.
Higher prices either reduce the consumption levels in a country and/or increase the production of the commodity whose relative price has increased. The magnitude of the changes in each country will depend on demand and supply elasticities of the commodities in question (Fig. 1.2). The flatter the demand and supply curves, the more elastic they are and the larger will be the quantity response and the lower the price change needed to clear the market.
The factor price equalization theorem has additional interesting implications.
Any tax or other restrictions on a particular good or factor of production will not affect the equalization of gross tax prices and or returns as long as the number of goods plus factors of productions free to move across national borders exceeds the numbers of factors of production. Factor returns will also be equalized across countries. However, what the restrictions do is, it alters the composition of products and or factors of production across national borders.
Again, the incidence of any tax or economic shock is influenced and determined by the mobility of the different factors of production and/or goods and services. In the example of this section any tax ultimately fall on the immobile factors, the local land.
This framework yields some other interesting insights regarding the implications of a policy of free trade and immigration restrictions, as well as implications of a policy of trade restrictions and free immigration with amnesty. The policy of free trade and immigration restrictions suggests that arbitrage in factor returns will take place through trade in goods. That is, goods will move across national borders while factors of production will remain in their native countries. In contrast, the factor return equilibrating process of a policy that restricts trade and allows free immigration will then take place through migrations of the factors of production. Clearly these two policies have different implications for population growth and the makeup of a country’s future population.
One final insight generated by this framework is an obvious one. If a country experiences either a man-made or natural disaster and the infrastructure is not rebuilt, it may not be possible to rearrange the productive machinery to absorb all the forces and equalize factor returns.
In that case, the abundant factor experiences a decline in its rate of return. One way to eliminate and arbitrage the differences is through the migration of the factor return to the area with a higher return. This is particularly applicable to the regions devastated by war and other political events. The failures of the developed world to help and implement a successful reconstruction effect have generated an out migration from the devastated areas into the more prosperous areas. The migration does not necessarily occur to super wealthy and developed economies. All that is needed is that the destination country has a higher standard of living or a better safety net than the country of origin.

Transportation Costs and Overall Equilibrium

Next we explore some additional insights derived through modifications to the basic framework by introducing transportation costs and other manmade artificial trade barriers, such as taxes and other restrictions. The broadly defined transportation costs may prevent the full equalization of prices and or factor returns across borders.
Example: the prevailing market clearing prices for a pound of cheese in Lakeland is 1 peso and the price in Westland is 2.50 pesos and it costs 1 peso to ship a pound of cheese from Lakeland to Westland and vice versa. How will the equilibrium including transportation costs differ from the one we have just discussed in the previous paragraphs?
Direct Arbitrage: Arbitrage and profit maximization will take care of the differences in prices less the “transportation or transaction costs” associated with moving the commodity, that is, cheese, across the national border. Profit maximization dictates that cheese will be exported from the low price locality, Lakeland, to the high price locality, Westland.
Initially, the transaction nets a gross profit of 1.50 per pound of cheese, which reduces the transportation costs and amounts to a net gain of 0.5 pesos.
As more cheese is exported from Lakeland the increased scarcity creates upward pressure on the local price. Conversely, the increased supply of cheese in Westland creates an incipient downward pressure on the local price. The net effect of all this being a decline in the price differential between the two localities, that is, a decline in the profits generated by the arbitrage.
The arbitrage, profit maximization generates an equilibrium process similar to the one described in the previous sections, depicted in Fig. 1.2.
The one difference being that a difference in prices less than or equal to the transportation costs are not profitable and hence these differences will not be arbitraged away. Simply put, the transportation costs produce equilibrium short of the unfettered equilibrium described in Fig. 1.2.
In the numerical example presented here, the process continues until the price differential falls to 1 peso, the transportation costs. At this point all the profit from shipping a pound of cheese has been arbitraged away.
Equilibrium requires that the global demand match global supply. A second necessary equilibrium condition is that the transportation costs introduce a wedge between the price paid by the importing country and the price received by the exporting country. The wedge or difference in national prices is nothing more than the “transportation costs.” The new equilibrium inclusive of transportation costs is shown graphically in Fig. 1.3. Notice that the two equilibrium conditions previously mentioned are satisfied in the graph:
  • The wedge or difference between the price paid by the importers in pesos, Pcntimage*E and the price received by the exporters, Pcptimage, is nothing more than the transportation costs, TC. In equation form, the wedge or price difference can be written as: TC = Pcntimage*EPcptimage
  • The global quantity demanded consumed, Qctimage, will match the global quantity supplied or produced, Qctimage.
image
Figure 1.3 Transportation cost and worldwide equilibrium.
(A) Country 1: Lakeland (peso), (B) country 2: Westland (in pesos), (C) world equilibrium.
A similar argument can be made that differences in excess of the transportation costs for a bottle of wine, 5 pesos, will also be arbitraged by exporting the wine from the locality where wine is lower priced, Westland, to the locality where wine is higher priced, Lakeland.
Arbitrage combined with transportation costs suggests that the differences in the price of a pound of cheese across national borders will not be higher than 1 peso and that of a bottle of wine not higher than 5 pesos. Any differences in price between the two localities that exceeds the transportation costs will be arbitraged away.
What else can we say? In order to further extend our analysis, we need to specify the prices of a bottle of wine and a pound of cheese. Let’s consider a scenario where the price of a pound of cheese in Lakeland is 10 pesos, while the price of a bottle of wine in Lakeland is 20 pesos. Since cheese is exported to Westland, the price of cheese in pesos in Westland will be the Lakeland price plus the transportation costs that is, 11 pesos. On the other hand, since wine is exported from Westland, the price of a bottle of wine in Westland will be Lakeland’s price less the transportation costs, that is, 15 pesos.
Notice that in this example, the transportation costs for the two commodities are not the same. The information presented in this paragraph can be used to show the following:
  • The transportation costs for the export of cheese account for 10% of the price of a pound of cheese in Westland.
  • The transportation costs for the import of a bottle of wine account for 25% of the price of a bottle of wine in Lakeland.
  • The ratio of the price of a pound of cheese and a bottle of wine show that in Lakeland it takes 100 bottles of wine to get 200 pounds of cheese.
  • However, in Westland it takes 100 bottles of wine to acquire 136 pounds of cheese.
In spite of the differences in prices in each economy, the numbers show that the transportation costs prevent any additional arbitrage of these differences in price across borders. A successful arbitrage process will ship the products from the relatively low price area to the relatively high price area. The calculations in the example given in the previous paragraph present some important information:
  • The rate of exchange in the two localities shows that cheese is relatively more expensive in Westland than in Lakeland.
  • The direct arbitrage opportunities have been exhausted; the peso prices of a pound of cheese and a bottle of wine in the two economies differ by exactly the transportation costs.
Another way of illustrating the arbitrage opportunities is as follows:
The data shows that wine is relatively more expensive in Lakeland than in Westland. Hence the arbitrage would need to find a means to: “effectively” ship cheese from Lakeland to Westland (i.e., as inexpensively as possible) and “effectively” ship wine from Westland to Lakeland. Think of the profit opportunity this way, removal of the transportation costs would generate an arbitrage opportunity. Since:
  • 100 bottles of wine in Westland fetches 136 pounds of cheese.
  • 100 bottles of Westland wine will fetch 200 pounds of cheese in Lakeland.
  • There therefore is a potential arbitrage gain of 74 pounds of cheese.
Unfortunately, this arbitrage opportunity is wiped out by the transportation costs, which for a bottle of wine is 25% of the price. Hence transporting 100 bottles to Lakeland yield a net profit of 75 bottles, which will only fetch 150 pounds of cheese. However the transportation costs for cheese is 10% and that means a net of 135 pounds of cheese will arrive at Westland after the transportation costs are deducted.
All the “low hanging fruit” or direct arbitrage has been taken and all that may be left is the “high hanging fruit,” indirect arbitrage.
Indirect Arbitrage: The issue for the arbitrageurs is how to get to the high hanging fruit? Direct arbitrage on the commodities market has eliminated any price difference other than the 25% transportation cost barrier.
In contrast for the cheese industry (the export sector) the producer is indifferent for selling at a 10% discount to the domestic consumers or charging full price inclusive of the transportation costs to the people of Westland.
Absent any mobility from one industry to another the factor returns in Lakeland’s wine industry has a 25% edge or protection from foreign competition, that is, the 25% transportation cost of a bottle of wine. At the margin the Lakeland industry can afford to pay 25% more and make the same profit as in the case when transportation costs are nonexistent. It will also make the same amount of revenues as any importer. On the other hand if it did not pay premium salaries, its profitability would include an additional 25% of the price per unit since Lakeland wine makers do not incur these transportation costs when they sell their wine locally. This situation however, would not stand for long, “competition” will attract new entrant into the local Lakeland wine-producing sector, thus increasing the domestic wine production.
In the latter case at the margin, the Lakeland wine industry would want to hire additional factors of production (i.e., additional skilled labor, etc.) this would result in an increase in the production of wine in Lakeland wine and that in turn would produce lower prices of wine in Lakeland. In order to attract the factors into wine production the Lakeland wine industry has to pay slightly higher salaries. And as more and more people are hired, the increased salaries result in an increase in marginal costs, the process continues until the marginal cost rise by 25%. At that point there will be no additional incentives to hire more workers and increase production.
The net effect of these changes will be a higher domestic wine production and a lower cheese production. That is, Lakeland’s imports of wine fall and so does Lakeland’s exports of cheese. The returns for the factors intensive in the production of wine rise relative to the factors intensive in the production of cheese. As the price of wine rises relative to the price of cheese, Lakeland’s relative prices converge to those of Westland.
In Westland the change in the market equilibrium is a mirror image of what happened in Lakeland. The cheese industry expands and so does the relative return of the factor intensive in the production of cheese. In turn the wine industry output declines. Again, cheese imports decline and so does the wine exports. Notice that in this scenario, the two countries react to minimize the relatively high transportation cost of wine, that is, the 25% transportation costs. On the other hand cheese, the product with the lower transportation costs of 10%, is the commodity that continues crossing borders in order to bring about a new equilibrium.
The conclusion here is that arbitrage, in a roundabout way, reduces and in some circumstances eliminates trade of the commodity with the highest transportation costs as a percent of the product price, in this example wine. If this process is successful, at equilibrium the price of cheese will differ across the two economies by 10%. In addition the price of wine will also differ by 10% across the two economies and will NOT differ by the 25% transportation costs of a bottle of wine (transportation of wine will no longer occur at the new equilibrium). Since the difference in prices across national borders is 10%, it follows that the relative prices of the two economies are the same. The indirect arbitrage ensures the equality of relative national borders irrespective of the transportation costs.
What the transportation costs and profit maximization do is to ensure the difference in absolute price differences across national borders matches the lowest transportation cost in the range of products traded internationally.

Mobility and the Incidence of Taxes and Other Economic Shocks

It is now time to expand the analysis to include mobility of factors of production across national boundaries. The assumption of profit maximization can be used to show that in the case of perfect mobility the differences in factor returns are arbitraged away.
Until now we have assumed fixed costs of moving across borders. This is analogous to buying a ticket on an airplane or paying a fixed cost to mail a package. The transportation costs considered range from zero to prohibitive, in the former case the factors and or products are free to move without any costs and in the latter the costs of moving are infinite. We have shown that if there are zero transportation costs, the differences in prices for similar products will be arbitraged away. And price disturbances will be transmitted across all economies and as a result will have a common qualitative effect across borders. The difference in the magnitude of the response will depend on the countries demand for and supply elasticities with respect to the price changes [12].
Arbitrage and mobility ensure that capital is rearranged in such a way that the after-tax rate of return is the same across industries, as well as across borders. The mobility assumptions yield some insights into the potential incidence and burden of different shocks and or economic policies.
Let’s take the case of an open economy that is very small in relation to the world economy. So small that it has no impact on world prices no matter what this economy does. In economic parlance, the small open economy is a “price taker.” This means that the unit cost for wine and cheese and the cost of capital are determined by the world market, that is the intersection of the world global demand and supply for the commodity in question and there is nothing the small country can do to alter the global price of these traded good and factors of production.
Now let’s consider the impact of a 10% tax on the price of the exported products, say cheese, in the small economy, and call it Lakeland for the time being. Since the country is a price taker, any export tax means that the net price received by the domestic producers will fall by 10% below the world price. That is,

Pc*×(1t)

image
where Pc*image is the worldwide equilibrium price for cheese and t is the export tax rate. A 10% tax in a product is equivalent to a tax on each for the factors of production. Labor is assumed to be free to move across national borders, this means that labor or any other mobile factor has to earn the same after tax rate of return as anywhere else in the world, We*image, otherwise it will leave the country in search of the higher rate of return. Therefore the salaries paid in Lakeland to the mobile factor have to be grossed by the tax.
Substituting these relationships into the costs of producing a pound of cheese in Lakeland, Eq. (1.25) we get:

Pc*×(1t)=[β*Wl+(1b)×R/(1t)]×(1t)

image(1.51)
Solving for the equilibrium wage rate

Wl=[Pc*×(1t)(1b)×R]/[b×(1t)]=(Pc*/b)+{(1b)×R/[b*(1t)]}

image(1.52)
Since Pc*image and W are determined in the world economy and we have assumed that the small economy, Lakeland, has no global market power. The only variable Lakeland can affect is the export tax rate. The previous equation shows that the increases in the tax rate lower the equilibrium wage rate. The incidence of the tax rate increase depends in the intensity of the immobile factor in the production of cheese. The lower the intensity of the immobile factor the greater the impact of the tax rate on the equilibrium rate of return of the immobile factor.
If, as we have assumed, capital is the perfectly mobile factor, the incidence of any tax on capital falls on the fixed factor of the country. This is the direct result that arbitrage ensures that the after-tax income remains the same across industries and countries. Given the unit labor costs, it means that as a result of the tax increase, there is less money available to be paid for the fixed factor. Hence a tax on the mobile factor lowers the rate of return of the fixed factor. The one insight derived from this is that the export tax falls completely on the domestic immobile tax, such as land or any other factor that is not able to move across the national border, that is, is unable to leave the country.
Given that the immobile factor of production is a fraction of the unit costs, it follows that the fluctuations in rates of return to the fixed factor is a magnified version of the fluctuations in the price of wine and cheese. The magnification factor is the inverse of the fraction of the fixed factor as share of unit costs, (1−β)/β.
The point that we want to make here is that the degree of mobility both across domestic industries and across the border has a significant impact on the incidence of different taxes and or economic shocks on the immobile or less mobile factor returns. The lack of mobility reduces the ability of these factors to shift the burden of the shock to other factors of production. Hence one should take into account the mobility of the factors of production and or the goods and services when analyzing the economic shocks on an economy’s overall equilibrium and its factor returns.
An investment insight is that one should want to increase exposure to the economy whose exchange rate is appreciating over and above the PPP relationship. In fact, an even better excess return is obtained by increasing exposure to the factors intensive in the production of the country’s exports.

The Speed of Adjustment to a New Equilibrium

Up to this point we have implicitly assumed that there is no adjustment costs in reaching a new equilibrium in the aftermath of an economic shocks such an increase in aggregate demand and or aggregate supply. If that is the case, the adjustment is instantaneous. Any profit opportunity that arises as the global economy moves from its preshock equilibrium to the new equilibrium is immediately arbitraged, as a result the new equilibrium is reached instantaneously.
However, in real life there may be adjustment costs. For example, it takes time to convert a field from pasture to winegrowing. It may take time to train people to acquire new skills etc., all of this suggests that the longer the time horizon the larger the long run elasticities of supply. Put another way there are costs associated with the speed of adjustment to a new equilibrium.
As long as the costs are positive the adjustment will not be instantaneous. This is a very important insight for investors with a global view. First it means that there will be a window of opportunity for investors who guess the new equilibrium. These investors will be able to earn an above average or excess return during the adjustment process to a new equilibrium.
If investors can anticipate the new equilibrium they may be able to approximate the adjustment path. This is where our framework comes into play, it may help us anticipate the new equilibrium. One final point is that the excess return or the will be a temporary one, once the new equilibrium is reached the excess returns disappear. Put another way, any edge that once can get from an approach as we have outlined here, will be a temporary one.

References

[1] Samuelson Paul A. International trade and the equalization of Factor Prices. Economic Journal. 1948;58:163184:June. Samuelson Paul A. International Factor Price Equalization Once Again. Economic Journal. 1949;59:181197:June.

[2] Mundell RA. International trade and factor mobility. Am Econ Rev. 1957;47(3):321335.

[3] Cassel KG. Abnormal deviations in international exchanges. Econ J. 1918; 413415.

[4] Canto VA. Cocktail economics. New Jersey: Pearson Education; 2007.

[5] Johnson HG. Two-sector model of general equilibrium. New York: Aldine-Atherton; 1971.

[6] Hicks JR. Value and capital. 2nd ed. 1939 Oxford: Oxford University Press; 1946.

[7] Frenkel JA, Levich RM. Covered interest arbitrage: unexploited profits?. J Political Econ. 1975;83(2):325338.

[8] Fisher I. The theory of interest. Philadelphia: Porcupine Press; 1977. [1930].

[9] Agmon T. The relations among equity markets: a study of stock price co-movements in the United states, United Kingdom, Germany and Japan. J Finance. 1972;27:839855.

[10] On this issue, see Stolper and Samuelson (1941). There is an extensive literature on the topic, find references to the Stolper-Samuelson theorem on the relationship between relative prices and relative actor returns. While the Factor Price Equalization Theorem, Samuelson (1948) relates the product prices to the factor absolute returns.

[11] Early on there were studies that challenged the validity of the Law of One Price such as Isard (1977) and Richardson (1978). There are several sources that give rise to these temporary deviations in some cases one may argue that they are the result of index measurements associated with changes in relative price changes. Another possibility is that the deviations are due to non-traded factors or goods specific to individual countries. These studies emphasize that measured prices can deviate for a sustained period. This fits our views of adjustment costs associated with terms of trade changes. Once the adjustment occurs, the relative prices remain unchanged and the composite good conditions applies once again.

[12] On this Issue see Canto and Webb (1987), Canto, Laffer, and Webb (1992).

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