# Again about Bing's house with two rooms [duplicate]

Possible Duplicate:
How to show that the “bing’s house with two rooms” is contractible?

I don't know why my question is closed? here, I make my question clearly, when "hollowing out the chambers",why two vertical rectangles (are inserted to form ‘support walls’ for the two tunnels) are left ? if remove them, it remain contractible?

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