/*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none} Problem 12 Simplify the Boolean expression ... [FREE SOLUTION] | 91Ó°ÊÓ

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Simplify the Boolean expression \((\overline{\bar{A} \cdot B})+(\overline{\bar{A}+B})\) by using de Morgan's laws and the rules of Boolean algebra. Applying de Morgan's law to the first term gives: \(\overline{\bar{A} \cdot B}=\overline{\bar{A}}+\bar{B}=A+\bar{B}\) since \(\overline{\bar{A}}=A\) Applying de Morgan's law to the second term gives: $$ \overline{\bar{A}+B}=\overline{\bar{A}} \cdot \bar{B}=A \cdot \bar{B} $$ Thus, \((\overline{\bar{A} \cdot B})+(\overline{\bar{A}+B})=(A+\bar{B})+A \cdot \bar{B}\) Removing the bracket and reordering gives: \(A+A\) : \(\bar{B}+\bar{B}\) But, by rule 15 , Table \(11.7, A+A \cdot B=A\), It follows that: \(A+A \cdot \bar{B}=A\) Thus: \((\overline{A \cdot B})+(\overline{\bar{A}+B})=A+\bar{B}\)

Short Answer

Expert verified
The simplified expression is \( A + \bar{B} \).

Step by step solution

01

Apply De Morgan's Law to the First Term

The first term of the expression is \( \overline{\bar{A} \cdot B} \). By De Morgan's law, we know that \( \overline{X \cdot Y} = \overline{X} + \overline{Y} \). Thus, applying De Morgan's law to the first term gives us: \( \overline{\bar{A}} + \bar{B} \). Since \( \overline{\bar{A}} = A \), this simplifies to \( A + \bar{B} \).
02

Apply De Morgan's Law to the Second Term

The second term of the expression is \( \overline{\bar{A} + B} \). Using De Morgan's law \( \overline{X + Y} = \overline{X} \cdot \overline{Y} \), we rewrite this as \( \overline{\bar{A}} \cdot \bar{B} \). Again, since \( \overline{\bar{A}} = A \), this simplifies to \( A \cdot \bar{B} \).
03

Combine the Results Using Boolean Algebra

Now the expression has been simplified to \( (A + \bar{B}) + (A \cdot \bar{B}) \). According to the Distributive Law of Boolean algebra, this can be rewritten as \( A + \bar{B} \), because \( A + A \cdot \bar{B} = A \) due to the Absorption Law.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

De Morgan's Laws
De Morgan's Laws are a fundamental part of Boolean algebra. They provide a way to transform expressions involving AND and OR operations. These laws help in simplifying expressions by changing complements of operations. Here are the two main formulas in De Morgan's Laws:

  • For conjunction (AND): \( \overline{X \cdot Y} = \overline{X} + \overline{Y} \)
  • For disjunction (OR): \( \overline{X + Y} = \overline{X} \cdot \overline{Y} \)
These laws are particularly useful when you need to simplify expressions with complex complements. In the problem given, De Morgan's laws were used to transform \( \overline{\bar{A} \cdot B} \) into \( \overline{\bar{A}} + \bar{B} \), which simplifies further to \( A + \bar{B} \). Again, applying the laws to \( \overline{\bar{A} + B} \) results in \( \overline{\bar{A}} \cdot \bar{B} \), which simplifies to \( A \cdot \bar{B} \).

Breaking down complicated expressions into a sequence of AND and OR transformations utilizing De Morgan's Laws helps to manage large Boolean equations effectively.
Boolean Expression Simplification
Simplifying Boolean expressions makes them easier to analyze and implement in digital circuits. The goal is to reduce the complexity of expressions without altering their truth values. This process involves applying Boolean algebra rules and laws to eliminate redundancies and reduce formula sizes.

Here are the steps involved in simplification:
  • Identify and apply relevant Boolean laws or rules, like De Morgan's Laws or absorption law.
  • Rearrange terms using commutative and associative laws.
  • Simplify using idempotent, null, and complement laws when applicable.
In our exercise, we started with the expression \( (\overline{\bar{A} \cdot B}) + (\overline{\bar{A} + B}) \). Using De Morgan's Laws initially, we rewrite each part and then combined them. The simplified version is \( A + \bar{B} \).

Simplification enhances efficiency in digital design, facilitating less complex and more cost-effective circuit implementations.
Absorption Law
The Absorption Law in Boolean algebra is a powerful tool for simplifying expressions. It states that combining a variable with its conjunction or disjunction negating another component can often be reduced. The basic forms of the Absorption Law are:

  • \( A + A \cdot B = A \)
  • \( A \cdot (A + B) = A \)
Using the absorption law, you can simplify expressions effectively. In our example, once we reach \( (A + \bar{B}) + (A \cdot \bar{B}) \), by applying \( A + A \cdot \bar{B} = A \), the expression reduces significantly.

Absorption helps eliminate redundant terms, ensuring that expressions are both minimal and efficient in implementation, crucial for optimizing digital systems.

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