Boolean Algebra Proof (Distribution and XOR)

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Discussion Overview

The discussion revolves around proving a distributive rule in Boolean algebra involving exclusive or (XOR). Participants explore the application of Boolean algebra theorems, particularly focusing on the use of XOR, DeMorgan's Rule, and the properties of Boolean operations.

Discussion Character

  • Homework-related
  • Mathematical reasoning
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant attempts to prove the distributive rule A*(B (XOR) C) = (A*B) (XOR) (A*C) using various Boolean algebra identities.
  • Another participant points out potential mistakes in the initial steps of the proof, specifically regarding the expression A*X+A*X' and the application of DeMorgan's Theorem.
  • A later reply acknowledges a correction regarding the use of DeMorgan's Rule, leading to a revised expression for the right-hand side of the equation.
  • There is a question raised about the simplification of terms A*A'*B and A'*A*C, with a suggestion that these terms equal zero due to the property A · A' = 0.

Areas of Agreement / Disagreement

Participants express differing views on the correctness of specific steps in the proof, and there is no consensus on the resolution of the initial attempts or the final proof structure.

Contextual Notes

Limitations include unresolved mathematical steps and the dependence on correct application of Boolean algebra rules. The discussion reflects uncertainty in the proof process and the handling of specific terms.

PhotonSSBM
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Homework Statement


Use the definition of exclusive or (XOR), the facts that XOR commutes and
associates (if you need this) and all the non-XOR axioms and theorems you know
from Boolean algebra to prove this distributive rule:

A*(B (XOR) C) = (A*B) (XOR) (A*C)

Homework Equations


All the boolean algebra theorems

The Attempt at a Solution


So here's what I've tried

A*(B (XOR) C)
=A*B*C' + A*B'*C
=A*X+A*X'
=A*1
=A*(X (XOR) X')

And

(A*B) (XOR) (A*C)
=A*B*(A*C)' + (A*B)'*B*C
=A*B*(A' + C') + (A' + B')*B*C
=A*B*A' + A*B*C' + A'*B*C + B'*B*C
=A*B*C' + A'*B*C
=B*(A (XOR) C)
I feel like I go in circles no matter what I do.
Any clues?
 
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PhotonSSBM said:
=A*X+A*X'
This looks wrong. :))
PhotonSSBM said:
=A*B*(A*C)' + (A*B)'*B*C
Mistake here, too. :H
 
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Oops, that's not how demorgans works...brb with corrections.
 
Ok, the answer came out once I realized how to use DeMorgan's Rule for the right hand side:

(A*B) (XOR) (A*C)
=(A*B) * (A*C)' + (A*B)' * (A*C)
=A*B * (A' + C') + (A' + B') * A*C
=A*A'*B + A*B*C' + A'*A*C + B'*A*C
=A*B*C' + A*B'*C
=A*(B*C' + B'*C)
=A* [B (XOR) C]

Thanks for the help!
 
Last edited:
in the next step:
=A*A'*B + A*B*C' + A'*A*C + B'*A*C
=A*B*C' + A*B'*C

what happened with (A*A'*B + A'*A*C)?
 
Hi,

Raimundo said:
what happened with (A*A'*B + A'*A*C)?

I think those go to zero as ## A \cdot \bar A = 0 ##
 
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