Solving Truth Tables & Writing WFFs with 2 Two-Place Connectives

In summary, the conversation discusses the task of finding wffs with exactly two two-place connectives. The first two wffs are given in a truth table format, while the last two require the use of algebraic or graphical methods. The conversation also addresses the use of negation (~) and the possibility of multiple solutions for a given wff.
  • #1
E92M3
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I was given a truth table and I must write a wff with exactly two two-place connective. I am new to logic and don't know where to start. I need to find wff a), b), c) and d).

C B A ... wff a)
T T T ... T
T T F ... F
T F T ... T
T F F ... F
F T T ... T
F T F ... T
F F T ... T
F F F ... T

A B C ...wff b)
T T T ... F
T T F ... T
T F T ... F
T F F ... F
F T T ... F
F T F ... T
F F T ... F
F F F ... T

I have no clue on these first two. I tried many but they all seemed not to work.

A B ... wff c)
T T ... F
T F ... T
F T ... T
F F ... T

I think I can do this one:
this is equivalent to ~(A&B) but I need to use two two place connectives so I wrote ~(A&(B&B)) is this correct? Also the question didn't specify whether I can use "~". can I use it anyway?

A ... wff d)
T ... T
F ... T

This one I can also manage but I'm not sure what is the right answer. This is equivalen to (Av~A) which I can write as ((A&A)v~A). However, I can also write ((A&A)->A) or ((A&A)<->A) aswell. I think there's a few more which is right?
 
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  • #2
The first step in the algebraic way is to write the minterm for the variables for each row where you see T as the outcome you leave all variables where the income is T as is, and negate those where the variable is F

for example
ABC
TFT = T
becomes
[tex]A\overline{B}C[/tex]

For a graphical solution you can draw the Karnaugh table of the function, and try to cover the T's with some (possibly overlapping) rectangular areas. You come up with the solution in a similar way, just now you can drop inputs where they are both T and F in the rectangle.

I would say that the question did not say anything about one-place connectives, so using "~" should be okay.
You are right that there can be more solutions to such a problem.
I see no errors in your solutions above.
 

FAQ: Solving Truth Tables & Writing WFFs with 2 Two-Place Connectives

What are truth tables and how are they useful in solving logical expressions?

Truth tables are a graphical representation of the possible combinations of values for a given set of variables in a logical expression. They are useful in solving logical expressions because they allow us to systematically analyze the truth values of each component of the expression, and determine the overall truth value of the expression. This helps us to understand the logical relationships between the variables and identify any inconsistencies or contradictions.

What are WFFs and how do they relate to truth tables?

WFFs (Well-Formed Formulas) are expressions that follow the rules of propositional logic and can be evaluated to either true or false. They are important in relation to truth tables because they are the basis for constructing logical expressions and determining their truth values. Truth tables are used to evaluate the validity of WFFs and to identify any logical errors that may be present.

What are two-place connectives and how do they affect truth tables and WFFs?

Two-place connectives are logical operators that operate on two variables to form a compound expression. Examples of two-place connectives include "and", "or", and "if-then". These connectives play a crucial role in constructing WFFs and determining their truth values. Truth tables are used to analyze the truth values of each component of the expression and the overall truth value of the compound expression.

What are the steps for solving truth tables and writing WFFs with two-place connectives?

The steps for solving truth tables and writing WFFs with two-place connectives are as follows:

  • 1. Identify the variables and their possible truth values.
  • 2. Use the two-place connectives to construct the logical expression.
  • 3. Create a truth table with columns for each variable and the final expression.
  • 4. Fill in the truth values for each possible combination of variables.
  • 5. Evaluate the truth value of the final expression for each row in the truth table.
  • 6. Use the truth table to identify any logical errors or contradictions in the expression.

What are some tips for solving truth tables and writing WFFs with two-place connectives?

Some tips for solving truth tables and writing WFFs with two-place connectives include:

  • 1. Familiarize yourself with the logical operators and their meanings.
  • 2. Pay attention to the order of operations and use parentheses to clarify the intended grouping of variables.
  • 3. Use shorthand symbols (such as ∧ for "and" and ∨ for "or") to simplify the expressions and save time.
  • 4. Double check your work and use the truth table to verify the accuracy of your solution.

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