4.1. FAKE NEWS EARLY DETECTION 57
          ˚ 
     a
i
 L  S D fs
1
; ; s
L
g  
 s
i
  
a
i
D v.s
1
/ ˚ v.s
2
/ ˚ v.s
L
/: 
              
     
User Response Generator
                
           
             
             
      C
.i/
D fc
i1
; ; c
i n
g     a  
       c   a     
z      
E
zq
.c
ij
;a
i
/
Πlog p
.c
ij
jz; a
i
/ C D
KL
.q
.zjc
ij
; a
i
//: 
              
     z      a
i
    
         q
.zjc; a/  
  p
.z/
    a          
             
             
              
    
4.1.2 AN EVENT-INVARIANT ADVERSARIAL APPROACH
            
              
event-specific            
               
               
  event-invariant          
             
             
  
58 4. CHALLENGING PROBLEMS OF FAKE NEWS DETECTION
            
          
             
           
               
              
 
.
.
.
.
.
.
.
.
.
.
.
.
Reddit,
has,
found,
a,
much,
clearer,
photo
Word
Embedding
Text
Feature
Multimodal
Feature
Text-CNN
Fake News Detector
Event Discriminator
Multimodal Feature Extractor
Visual Feature
VGG-19
vis-fc
reversal
adv-fc1
adv-fc2
pred-fc
Concatenation
R
T
R
F
R
V
.
.
.
              
           
 
Multi-Modal Feature Extractor
            
          
               
   R
cnn
           
R
vgg
            
            
R
T
D .W
t
/R
cnn
R
V
D .W
v
/R
vgg
:

4.1. FAKE NEWS EARLY DETECTION 59
   R
T
    R
V
      
     R
F
D R
T
˚ R
V
       
  
Fake News Detector
             
                
   R
F
           
      
min L
d
.
f
;
d
/ WD min EŒy log.P
.a// C .1 y/.log.1 P
.a///; 
 a   
f

d
        
             
                 
                
            
         
Event Discriminator
            
               
             
          E  .1; ; e/   
           
min L
e
.
f
;
e
/ WD min E
"
E
X
kD1
1
ŒkDy
e
log.G
e
.G
f
.aI
f
//I
e
/
#
; 
 G
f
     y
e
     
 G
e
          
            
             
            L
e
  
 
f
           
              
             
            
             
      
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