1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Prove absorption law

  1. Sep 14, 2011 #1
    1. The problem statement, all variables and given/known data

    Prove the absorption law A U (A and B) = A

    2. Relevant equations

    3. The attempt at a solution

    I need to prove the sets are equal.

    I don't know how to prove the right hand as a subset of the left hand.
    For left hand as subset of right hand, it's pretty simple (we can define a new called G holding x in A and in B), and G is subset of A, then G U A is A (definition of subset and Union).

    But how do I prove the right hand?
    I started writing "There exists a set A...." and I thought about using partition, but then I couldn't go on anymore. If I say there exists an arbitrary set B, and x in A and B, then I am again writing the first proof.

    Can someone please help me? Thanks.
  2. jcsd
  3. Sep 15, 2011 #2


    User Avatar

    Staff: Mentor

    Is this set theory or Boolean Algebra? Boolean Algebra I think.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Similar Threads for Prove absorption
Given this modification to Euclid's algorithm, prove [...]