Boolean Algebra Proof (Distribution and XOR)

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SUMMARY

The forum discussion focuses on proving the distributive rule of exclusive or (XOR) in Boolean algebra: A*(B XOR C) = (A*B) XOR (A*C). The user initially attempts the proof using various Boolean algebra theorems but encounters errors, particularly in applying DeMorgan's Rule. After corrections, the user successfully demonstrates the proof by simplifying both sides and recognizing that terms like A*A' equal zero. The final proof confirms the distributive property holds true in this context.

PREREQUISITES
  • Understanding of Boolean algebra principles
  • Familiarity with exclusive or (XOR) operations
  • Knowledge of DeMorgan's Theorems
  • Ability to manipulate Boolean expressions
NEXT STEPS
  • Study Boolean algebra theorems in detail
  • Learn advanced applications of DeMorgan's Theorem
  • Explore practical examples of XOR in digital circuit design
  • Investigate the implications of distributive properties in Boolean functions
USEFUL FOR

Students of computer science, electrical engineering, and anyone studying digital logic design who seeks to deepen their understanding of Boolean algebra and its applications.

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
 
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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