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Give a truth table for the expression $$ f=\bar{p} \cdot q \cdot \bar{r}+\bar{p} \cdot q \cdot r+p \cdot \bar{q} \cdot \bar{r}+p \cdot q \cdot r $$

Short Answer

Expert verified
The truth table has 1's when \( p, q, r \) are combinations: 010, 011, 100, and 111.

Step by step solution

01

Identify Variables

The given expression is in terms of variables \( p \), \( q \), and \( r \). Therefore, list these variables as the columns in the truth table along with \( f \), the result of the expression.
02

Determine Possible Combinations

For three variables \( p \), \( q \), and \( r \), there are \( 2^3 = 8 \) possible combinations of truth values (true or false). List these combinations in binary format: 000, 001, 010, 011, 100, 101, 110, 111 where 0 represents false and 1 represents true.
03

Evaluate Expression for Each Combination

For each row in the truth table, substitute the values of \( p \), \( q \), and \( r \) into the expression \( f = \overline{p} \cdot q \cdot \overline{r} + \overline{p} \cdot q \cdot r + p \cdot \overline{q} \cdot \overline{r} + p \cdot q \cdot r \) and compute the result:1. For \( p = 0 \), \( q = 0 \), \( r = 0 \), evaluate to 0.2. For \( p = 0 \), \( q = 0 \), \( r = 1 \), evaluate to 0.3. For \( p = 0 \), \( q = 1 \), \( r = 0 \), evaluate to 1.4. For \( p = 0 \), \( q = 1 \), \( r = 1 \), evaluate to 1.5. For \( p = 1 \), \( q = 0 \), \( r = 0 \), evaluate to 1.6. For \( p = 1 \), \( q = 0 \), \( r = 1 \), evaluate to 0.7. For \( p = 1 \), \( q = 1 \), \( r = 0 \), evaluate to 0.8. For \( p = 1 \), \( q = 1 \), \( r = 1 \), evaluate to 1.
04

Compile the Truth Table

Using the evaluations from Step 3, compile the truth table:\[ \begin{array}{ccc|c}p & q & r & f \\hline0 & 0 & 0 & 0 \0 & 0 & 1 & 0 \0 & 1 & 0 & 1 \0 & 1 & 1 & 1 \1 & 0 & 0 & 1 \1 & 0 & 1 & 0 \1 & 1 & 0 & 0 \1 & 1 & 1 & 1 \ \end{array} \]

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Key Concepts

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

Boolean Algebra
Boolean algebra is a branch of algebra that deals with true or false values. Instead of usual arithmetic values, Boolean algebra uses logical values (often represented as 0 for false and 1 for true). It is foundational in designing circuits and logical expressions used primarily in computer science and engineering fields.

Key operations in Boolean algebra include:
  • AND (\(\cdot\) or sometimes \(\land\)): Where all inputs must be true for the output to be true.
  • OR (\(+\) or \(\lor\)): Where at least one input must be true for the output to be true.
  • NOT (\(\overline{\,}\) or \(eg\)): It inverts the value, making true false and vice versa.


Applying these principles in Boolean algebra can help simplify complex logical expressions, making them easier to implement in hardware or software.
Logical Expressions
Logical expressions are combinations of variables and logical operations in Boolean algebra. They are used to derive conclusions based on logical reasoning. Each variable in a logical expression represents a statement that can be true or false.

Consider the logical expression from the exercise: \(f = \overline{p} \cdot q \cdot \overline{r} + \overline{p} \cdot q \cdot r + p \cdot \overline{q} \cdot \overline{r} + p \cdot q \cdot r\). Here, the logical operations are combined to determine the expression's truth value for different values of variables \(p\), \(q\), and \(r\).

Each term in the expression (such as \(\overline{p} \cdot q \cdot \overline{r}\)) is an AND operation among the variables or their negations. The OR operation is used to combine these terms, determining if the complete statement is true.

When working with logical expressions, truth tables become indispensable tools. They systematically show how the values of logical variables affect the overall expression's truth value.
Engineering Mathematics
Engineering mathematics involves using mathematical concepts and tools to solve practical problems faced in engineering. Logical expressions and Boolean algebra are integral parts of this field, particularly in areas related to computer and electrical engineering.

These mathematical tools allow engineers to design and analyze electric circuits, hardware logic, and software algorithms. By representing electronic circuits or digital logic using Boolean algebra, engineers can simulate and optimize circuit behavior before physically building it.

For example, logical expressions might be used in circuit design to create a desired output, as they can represent switches, gates, and circuits. Engineers can apply simplification techniques to minimize the components required for a circuit, resulting in cost-effective and efficient designs. With a deep understanding of Boolean algebra and logic, engineers can design robust systems and troubleshoot existing ones effectively.

In summary, engineering mathematics provides the foundation for creating innovative technologies, enabling solutions to complex problems through a structured and precise approach.

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Most popular questions from this chapter

Four engineers J, F, H and D are checking a rocket. Each engineer has a switch that he or she presses in the event of discovering a fault. Show how these must be wired to a warning lamp, in the countdown control room, if the lamp is to light only under the following circumstances: (a) D discovers a fault; (b) any two of \(\mathrm{J}, \mathrm{F}\) and \(\mathrm{H}\) discover a fault.

Simplify the following Boolean functions and sketch the logic block corresponding to both the given and simplified functions: (a) \((\bar{p} \cdot q+p \cdot \bar{q}) \cdot(\bar{p}+\bar{q}) \cdot(p+q)\) (b) \(\bar{r} \cdot \bar{p} \cdot \bar{q}+\bar{r} \cdot \bar{p} \cdot q+r \cdot \bar{p} \cdot \bar{q}\) (c) \(\bar{p} \cdot \bar{q}+r \cdot \bar{p} \cdot s+\bar{p} \cdot \bar{q} \cdot s\) (d) \((p+q) \cdot(p+r)+r \cdot(p+q \cdot r)\) (e) \((\bar{p}+\bar{q}) \cdot(\bar{p}+q) \cdot(p+q)\)

Which of the following statements are propositions? For those that are not, say why and suggest ways of changing them so that they become propositions. For those that are, comment on their truth value. (a) Julius Caesar was prime minister of Great Britain. (b) Stop hitting me. (c) Turn right at the next roundabout. (d) The Moon is made of green cheese. (e) If the world is flat then \(3+3=6\). (f) If you get a degree then you will be rich. (g) \(x+y+z=0\). (h) The 140th decimal digit in the representation of \(\pi\) is 8 . (i) There are five Platonic solids.

A panel light in the control room of a satellite launching site is to go on if the pressure in both the oxidizer and fuel tanks is equal to or above a required minimum value and there are 15 minutes or less to 'lift-off', or if the pressure in the oxidizer tank is equal to or above the required minimum value and the pressure in the fuel tank is below the required minimum value but there are more than 15 minutes to 'lift-off', or if the pressure in the oxidizer tank is below the required minimum value but there are more than 15 minutes to 'lift-off'. By using a truth table, write down a Boolean expression to represent the state of the panel light. Minimize the Boolean function.

Defining the difference \(A-B\) between two sets \(A\) and \(B\) belonging to the same universal set \(U\) to be the set of elements of \(A\) that are not elements of \(B\), that is \(A-B=A \cap \bar{B}\), verify the following properties: (a) \(U-A=\bar{A}\) (b) \((A-B) \cup B=A \cup B\) (c) \(C \cap(A-B)=(C \cap A)-(C \cap B)\) (d) \((A \cup B) \cup(B-A)=A \cup B\) Illustrate the identities using Venn diagrams.

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