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for j =1 , 2 ,...,W . It is an approximation of the local patterns v ( w l )
of
i
the original delay matrix X ( w l ) , for window size w l = w 0 W l .
Consider v0 (100 , 1)
in our example. The first k =2outof kW =4num-
1
bers in v (100 , 1)
approximate the patterns among the 2-dimensional vec-
1
tors p (100 , 0)
( j ) , which in turn capture patterns among the 100-dimensional
vectors x (100 , 0)
( i ) of the original time-delay matrix. Thus, but forming the
appropriate linear combination of the 100-dimensional patterns v (100 , 0)
i
v0 (100 , 0)
(i.e., the columns of V (100 , 0)
V0 (100 , 0) ), weighted according
to v (100 , 1 1 [1 : 2], we can construct the first half of the 200-dimensional
pattern v0 (100 , 1 1 [1 : 100] (left-slanted entries in Figure 5.6 ) . Similarly, a
linear combination of the columns of V (100 , 0)
i
V0 (100 , 0) weighted ac-
cording to v (100 , 1)
1 [3 : 4] gives us the second half of the 200-dimensional
pattern v0 (100 , 1 1 [101 : 200] (right-slanted entries in Figure 5.6 ). For
level l = 2 we similarly combine the columns of V0 (100 , 1) according to
v (100 , 2)
[1 : 2] (for the first half, v0 (100 , 2)
[1 : 200]) and to v (100 , 2)
[
3 : 4] (for
1
1
the second half, v0 (100 , 2)
[201 : 400]) and so on, for the higher levels.
1
Lemma 5.12 (Orthonormality of v0 ( w 0 ,l )
) We have
i
= j , v0 ( w 0 ,l )
T v0 ( w 0 ,l )
=0 ,where i,j =
v0 ( w 0 ,l )
=1 and, for i
i
i
j
1 , 2 ,...,k .
Proof. For level l = 0 they are orthonormal since they coincide with
the original patterns v ( w 0 i which are by construction orthonormal. We
proceed by induction on the level l
1. Without loss of generality,
assume that k = 2 and, for brevity, let B V0 ( w 0 ,l− 1) and b i, 1
v ( w 0 ,l )
[1 : k ], b i, 2 v ( w 0 ,l )
[ k +1: k ], so that v ( w 0 ,l )
=[ b i, 1 , b i, 2 ]. Then
i
i
i
v0 ( w 0 ,l )
2 =[ Bb i, 1 Bb i, 2 ] 2 = Bb i, 1
2 + Bb i, 2
2
i
v ( w 0 ,l )
2 +
2 =
2 =1 ,
=
b i, 1
b i, 2
i
and
v0 ( w 0 ,l )
T v0 ( w 0 ,l )
=[ Bb i, 1 Bb i, 2 ] T [ Bb j, 1 Bb j, 2 ]
= b i, 1 B T Bb j, 1 + b i, 2 B T Bb j, 2
= b i, 1 b j, 1 + b i, 2 b j, 2
= v ( w 0 ,l )
i
j
T v ( w 0 ,l )
=0 ,
i
j
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