Understanding Absorption Laws (Boolean Algebras)

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SUMMARY

The discussion focuses on the Absorption Laws in Boolean Algebras, specifically the expression a ∨ (a ∧ b) and its simplification. Participants clarify that the expression can be rewritten as (a ∧ ⊤) ∨ (a ∧ b) and further simplified to a ∧ (T ∨ b), ultimately concluding that a ∨ (a ∧ b) simplifies to a. The confusion arises from the application of the distribution law, which is essential for deriving the correct form of the expression.

PREREQUISITES
  • Understanding of Boolean Algebra concepts
  • Familiarity with Absorption Laws
  • Knowledge of distribution law in Boolean expressions
  • Ability to construct and interpret truth tables
NEXT STEPS
  • Study the detailed workings of Boolean Algebra Absorption Laws
  • Learn how to apply distribution law in Boolean expressions
  • Practice constructing truth tables for various Boolean expressions
  • Explore additional resources on ProofWiki for Boolean Algebra proofs
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This discussion is beneficial for students of mathematics, computer science professionals, and anyone interested in deepening their understanding of Boolean Algebra and its applications in logic and digital circuit design.

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TL;DR
I cannot apply distribution law
I can't understand how absorption law is obtained. I get following steps.##a∨(a∧𝑏) = (a∧⊤)∨(a∧𝑏)##
##=(a∨a)∧(a∨b)∧(⊤∨a)∧(⊤∨b)##
then,

I come up with ##=a∧(a∨b)∧⊤∧⊤## so ##=a∧(a∨b)##

But, I cannot get ##a∧(⊤∨𝑏)##, as shown on here, therefore ##a##.

Can you help me? I cannot obtain ##a∧(⊤∨𝑏)## Some people say in other answers in different questions, it is obtained by distribution law. However, what I got by this is the first equation.
[1]: https://proofwiki.org/wiki/Absorption_Laws_(Boolean_Algebras)
 
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mathrookie said:
TL;DR Summary: I cannot apply distribution law

I can't understand how absorption law is obtained. I get following steps.##a∨(a∧𝑏) = (a∧⊤)∨(a∧𝑏)##
##=(a∨a)∧(a∨b)∧(⊤∨a)∧(⊤∨b)##
Your expression above doesn't help.
Follow the logic in your link to get this:
##a ∨ (a∧𝑏) = (a∧⊤)∨(a∧𝑏)##
##= a ∧ (T ∨ b) ## ∧ distributes over ∨
## = a ∧ T = a## T ∨ b = T
Edited to fix earlier typo.
mathrookie said:
then,

I come up with ##=a∧(a∨b)∧⊤∧⊤## so ##=a∧(a∨b)##

But, I cannot get
##a∧(⊤∨𝑏)##, as shown on here, therefore ##a##.

Can you help me? I cannot obtain
##a∧(⊤∨𝑏)## Some people say in other answers in different questions, it is obtained by distribution law. However, what I got by this is the first equation.
[1]: https://proofwiki.org/wiki/Absorption_Laws_(Boolean_Algebras)
 
Last edited:
Mark44 said:
Your expression above doesn't help.
Follow the logic in your link to get this:
##a ∨ (a∧𝑏) = (a∧⊤)∨(a∧𝑏)##
##= a ∧ (T ∧ b) ## ∧ distributes over ∨
## = a ∧ T = a## T ∨ b = T
Slight typo here, should be ##a\wedge(\top\vee b)##
OP, you can also use a truth table to see that the two expressions must be equal to a.
 
TeethWhitener said:
Slight typo here, should be ##a\wedge(\top\vee b)##
Right. I've fixed it in my post.
 
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