I = I
1
X
I
1
X
I
2
= X − X
I
1
X
I
1
X
I
2
F
(1)
F
(2)
F = F
(1)
+ F
(2)
X
I
1
X
I
2
I
1
, . . . , I
m
X
I
1
, . . . , X
I
m
X = [X
1
: . . . : X
K
]
F F = F
(1)
+ F
(2)
F
(1)
F
(2)
{1, . . . , d} I {1, . . . , d}\I m = 2
U
1
, . . . , U
d
L
(L)
L
(L)
L
(L,1)
= L(U
i
, i ∈ I)
L
(L,2)
= L(U
i
, i 6∈ I) U
i
, i ∈ I U
i
, i 6∈ I
F
(1)
F
(2)
X
I
X
1
, . . . , X
K
L
(L,1)
F
(1)
U
i
V
i
λ
i
X
i