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Table 1 Main tensor models

From: Overview of constrained PARAFAC models

Models

Scalar writings

Mode‐ n product‐based writings

PARAFAC‐3

x i 1 , i 2 , i 3 = r R a i 1 , r ( 1 ) a i 2 , r ( 2 ) a i 3 , r ( 3 )

X= I 3 , R × 1 A ( 1 ) × 2 A ( 2 ) × 3 A ( 3 )

Tucker‐3

x i 1 , i 2 , i 3 = r 1 = 1 R 1 r 2 = 1 R 2 r 3 = 1 R 3 g r 1 , r 2 , r 3 a i 1 , r 1 ( 1 ) a i 2 , r 2 ( 2 ) a i 3 , r 3 ( 3 )

X=G × 1 A ( 1 ) × 2 A ( 2 ) × 3 A ( 3 )

Tucker‐(2,3)

x i 1 , i 2 , i 3 = r 1 = 1 R 1 r 2 = 1 R 2 g r 1 , r 2 , i 3 a i 1 , r 1 ( 1 ) a i 2 , r 2 ( 2 )

X=G × 1 A ( 1 ) × 2 A ( 2 )

PARALIND/CONFAC‐3

x i 1 , i 2 , i 3 = r 1 = 1 R 1 r 2 = 1 R 2 r 3 = 1 R 3 g r 1 , r 2 , r 3 a i 1 , r 1 ( 1 ) a i 2 , r 2 ( 2 ) a i 3 , r 3 ( 3 )

X=G × 1 A ( 1 ) × 2 A ( 2 ) × 3 A ( 3 )

 

g r 1 , r 2 , r 3 = r R φ r 1 , r ( 1 ) φ r 2 , r ( 2 ) φ r 3 , r ( 3 )

G= I 3 , R × 1 Φ ( 1 ) × 2 Φ ( 2 ) × 3 Φ ( 3 )

PARATUCK‐2

x i 1 , i 2 , i 3 = r 1 = 1 R 1 r 2 = 1 R 2 g r 1 , r 2 , i 3 a i 1 , r 1 ( 1 ) a i 2 , r 2 ( 2 )

X=G × 1 A ( 1 ) × 2 A ( 2 )

 

g r 1 , r 2 , i 3 = c r 1 , r 2 φ r 1 , i 3 ( 1 ) φ r 2 , i 3 ( 2 )

G= I 3 , R × 1 Ψ ( 1 ) × 2 Ψ ( 2 ) × 3 F, R=R1R2

  

Ψ ( 1 ) = I R 1 1 R 2 T , Ψ ( 2 ) = 1 R 1 T I R 2

  

F=(Φ(1)Φ(2))Tdiag(vec(CT))

PARATUCK‐(2,4)

x i 1 , i 2 , i 3 , i 4 = r 1 = 1 R 1 r 2 = 1 R 2 g r 1 , r 2 , i 3 , i 4 a i 1 , r 1 ( 1 ) a i 2 , r 2 ( 2 )

X=G × 1 A ( 1 ) × 2 A ( 2 )

 

g r 1 , r 2 , i 3 , i 4 = c r 1 , r 2 , i 4 φ r 1 , i 3 ( 1 ) φ r 2 , i 3 ( 2 )

G= I 4 , R × 1 Ψ ( 1 ) × 2 Ψ ( 2 ) × 3 F × 4 D, R=R1R2

  

Ψ ( 1 ) = I R 1 1 R 2 T , Ψ ( 2 ) = 1 R 1 T I R 2

  

F= ( Φ ( 1 ) Φ ( 2 ) ) T ,D= C I 4 × R 1 R 2