Understanding Absorption Laws (Boolean Algebras)

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In summary: Thanks.In summary, the absorption law is obtained by using the distributive law in Boolean Algebras. This allows for the expression to be simplified to ##a∧(a∨b)## and ultimately to ##a##. Some people may refer to it as distribution law, but it is the same concept.
  • #1
mathrookie
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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)##
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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  • #2
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:
  • #3
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.
 
  • #4
TeethWhitener said:
Slight typo here, should be ##a\wedge(\top\vee b)##
Right. I've fixed it in my post.
 
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1. What are absorption laws in Boolean algebras?

Absorption laws are a set of rules that govern the behavior of logical operators in Boolean algebras. These laws state that when a logical operator is applied to a set of variables and their negations, the result will be the same as if the operator was only applied to the variables. In other words, the operator "absorbs" the negation of the variables.

2. Why are absorption laws important in Boolean algebras?

Absorption laws are important because they allow us to simplify complex logical expressions. By applying these laws, we can reduce the number of variables and operators in an expression, making it easier to understand and manipulate. This is especially useful in computer science and digital logic, where Boolean algebra is used to represent and manipulate binary data.

3. How do absorption laws work in practice?

In practice, absorption laws are applied by looking for patterns in logical expressions. For example, the first absorption law states that A ∨ (A ∧ B) = A. This means that if we have an expression with the form A ∨ (something), we can simplify it to just A. Similarly, the second absorption law states that A ∧ (A ∨ B) = A, so if we have an expression with the form A ∧ (something), we can simplify it to just A. By recognizing these patterns and applying the absorption laws, we can simplify even the most complex logical expressions.

4. Can absorption laws be used with all logical operators?

Yes, absorption laws can be used with all logical operators, including AND, OR, and NOT. However, they are most commonly used with the AND and OR operators. This is because these operators have the property of distributivity, which is necessary for the absorption laws to hold. The NOT operator does not have this property, so absorption laws are not as useful when working with negated variables.

5. Are there any limitations to absorption laws?

While absorption laws are very useful in simplifying logical expressions, they do have some limitations. These laws only work when the logical operators are applied to variables and their negations. If the operators are applied to more complex expressions, such as (A ∧ B) ∨ (C ∧ D), the absorption laws do not apply. Additionally, absorption laws cannot be used to simplify expressions with more than two variables, so they may not be applicable in all situations.

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