4.3. EXPLAINABLE FAKE NEWS DETECTION 71
        a       
O
a
k
D e
k
˚ Na 
           
a
0
k
D f .W
a
Oa
k
C b
a
/; 
 W
a
 b
a
         f   
              ˛
k
            
˛
k
D
exp.a
0
k
/
P
k
exp.a
0
k
/
: 
       < h
k
>       
 < ˛
k
>             
             
r D
1
k
X
k
˛
k
h
k
: 
     r        ep  
  p     
l D relu.W
c
.r ˚ ep ˚ p/ C b
c
/: 
Claim Credibility Prediction
      y       
  
e D softmax.l/: 
               
         
y D
1
L
X
j
e
j
: 
4.3.2 A SOCIAL CONTEXT-AWARE APPROACH
              
              
            
72 4. CHALLENGING PROBLEMS OF FAKE NEWS DETECTION
 
          
               
                 
             
             
             
            related 
                
               
 St. Nicholas was white? Really??Lol        
  The Holy Book always said Santa Claus was white
               
          
 a      L  fs
i
g
L
iD1
  s
i
D
fw
i
1
; ; w
i
M
i
g  M
i
  C D fc
1
; c
2
; :::; c
T
g    T   
  a    c
j
D fw
j
1
; ; w
j
Q
j
g  Q
j
   
             
       y D 1   y D 0        
  RS     fs
i
g
L
iD1
   RC     fc
j
g
T
j D1
       RS
k
RC
k
  k
th
  
             
             
               
https://www.politifact.com/
4.3. EXPLAINABLE FAKE NEWS DETECTION 73
           
            
            
         
      
s
S C
s
s
ŷ: Softmax
[ŝ,ĉ]: Concate
ĉ: Product
a
c
: Softmax
H
c
: Sum
L
T
: Product
ŝ: Product
a
s
: Softmax
H
s
: Sum
L: Product
α

α

α
M
β

β

β
M
h
h
h
N
v
o
w
o
c
v
v
N
h
h
h
N
h

h

h
M
w

w

w
M
h

h

h
M
c
c
c
T
······
······
······
······
······
······
······
h

h

h
Q
w

w

w
Q
h

h

h
Q
······
······
······
······
······
Sentence-Comment
Co-attention
Fake News
Prediction
Sentence Encoder
Comments Encoder
Word Encoder
             
          
           
            
           
74 4. CHALLENGING PROBLEMS OF FAKE NEWS DETECTION
            
         
             
           
           
            
  
News Contents Encoding          
            
              
            
              
     Pence: Michelle Obama is the most vulgar first lady we've
ever had   vulgar          
       
           
            
            
         
          
              
    
Word Encoder          
              
               
            
          
         
             
   
!
f    s
i
  w
i1
 w
iM
i
  
f    s
i
  w
iM
i
 w
i1
!
h
it
D
!
GRU.w
it
/; t 2 f1; : : : ; M
i
g
h
it
D
GRU.w
it
/; t 2 fM
i
; : : : ; 1g:

      w
it
     
!
h
it

  
h
it
 h
it
D Œ
!
h
it
;
h
it
       
   w
it
4.3. EXPLAINABLE FAKE NEWS DETECTION 75
             
             
       v
i
2 R
2d1
   
v
i
D
M
i
X
tD1
˛
it
h
it
; 
 ˛
it
    t
th
    s
i
 ˛
it
   
o
it
D .W
w
h
it
C b
w
/
˛
it
D
exp.o
it
o
T
w
/
P
M
i
kD1
exp.o
ik
o
T
w
/
;

 o
it
     h
it
      h
it
  
   o
w
         
Sentence Encoder            
              
         h
i
   
 v
i
            
!
h
i
D
!
GRU.v
i
/; i 2 f1; : : : ; Lg
h
i
D
GRU.v
i
/; i 2 fL; : : : ; 1g:

      s
i
2 R
2d1
     
!
h
i
   
h
i
 s
i
D Œ
!
h
i
;
h
i
     
   s
i
User Comments Encoding         
            
               
             
               
              
              
              
     c
j
  w
jt
; t 2 f1; ; Q
j
g   
  w
jt
    w
jt
2 R
d
       
    
!
h
jt
   
h
jt
 
!
h
jt
D
!
GRU.w
jt
/; t 2 f1; : : : ; Q
j
g
h
jt
D
GRU.w
jt
/; t 2 fQ
j
; : : : ; 1g:

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