A"

B"

B

A

B'

A'

B

B

_

A"

B'

B"

A'=l'

B

o

B

_

l"

A"

B"

C"

C'

B'

A'

W'

W"

1"=2"

I'

II'

1'

2'

I

∈1

W

⇓

I'

∈

1'W'

I"

∈

1"W"

I" =II"

1

∈

AB

⇓

1'

∈

A'B'

1"

∈

A"B"

II

∈

W2

⇓

II'

∈

2'W'

II"

∈

2"W"

2

∈

AC

⇓

2'

∈

A'C'

2"

∈

A"C"