Math Help - Sets Problem

Are the following statements true :
1. A Ç B¢ = ÆÞ A Ì B

But I think it should be
A Ç B¢ = ÆÞ A Í B

2. A¢È B = U Þ A Ì B
But I think it should be
A¢È B = U Þ A Í B

3.(A – B) È B = A iff B Ì A
But I think it should be
(A – B) È B = A iff B Í A

Plz tell me I am wrong or book is wrong. Plz give ur answer with reason. I don’t want mathematical proof for the correct statements. If possible , plz verify the statement that u say correct or wrong.

Originally Posted by goodone

Are the following statements true :
1. A Ç B¢ = ÆÞ A Ì B

But I think it should be
A Ç B¢ = ÆÞ A Í B

2. A¢È B = U Þ A Ì B
But I think it should be
A¢È B = U Þ A Í B

3.(A – B) È B = A iff B Ì A
But I think it should be
(A – B) È B = A iff B Í A

Plz tell me I am wrong or book is wrong. Plz give ur answer with reason. I don’t want mathematical proof for the correct statements. If possible , plz verify the statement that u say correct or wrong.

Check the definition of the two subset relations in the source for the questions, some authors use to denote a subset not necessarily a proper subset.

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Author is using Ì to denote the proper subset and Í to denote the subset.

Originally Posted by goodone

Author is using Ì to denote the proper subset and Í to denote the subset.

Then clearly something is wrong, try seeing what happens when A=B to show this (the lefthand sides of the implication hold but the right hand sides do not.

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