Assign Yourself and Do Now
This guide explains the fundamental concepts of truth tables in logic, focusing on tautologies and logical contradictions. It provides real-world examples to illustrate compound propositions, emphasizing the significance of the logical operators "and" (∧) and "or" (∨). You'll learn how to construct truth tables for different logical expressions, determine if they are tautologies, contradictions, or neither, and understand logical equivalence. Additionally, practical exercises are suggested to help solidify your understanding and prepare you for quizzes on logical reasoning.
Assign Yourself and Do Now
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Assign Yourself and Do Now Thursday, January 10, 2013
Truth Table Explanation It will always be true – since OR means at least one, and they are opposites, one of them will be true always. Do Now Explanation
In words, p v ¬q: Truth Table Sponge Bob lives under the sea or Sponge Bob and Patrick are not friends. Sponge Bob and Patrick
When Sponge Bob lives under the sea • When Spongebob and Patrick are not friends • Both Under what conditions is p v ¬q true?
Tautology Logical Contradiction A compound proposition is a logical contradiction if all the values in its truth table column are false. A compound proposition is a tautology if all the values in its truth table column are true. New Definitions
p v ¬p – truth table Conclusion? It is a tautology because all the values in the p v ¬p column are TRUE. Determine if p v ¬p is a tautology, a logical contradiction or neither
(p ^ q) ^ ¬ (p v q) is a logical contradiction because all of the values in its column are false. Tautology, Logical Contradiction or Neither?
Meaning in Words Truth Table ¬(p^q) = ¬(Brittany likes volleyball and math) = Brittany does not like both volleyball and math (she dislikes at least one). ¬(p^q)
Meaning in Words Truth Table ¬p v ¬q = Brittany does not like volleyball or Brittany does not like math(or both). This is neither a tautology nor a logical contradiction because the last column is not purely T or F. ¬p v ¬q
¬ (p ^ q) Truth Table ¬ p v ¬ q Truth Table If two truth tables have the same end result, then the two statements are logically equivalent. Compare the Two!
Make your columns: p, q, r, ¬ r, p v q, (p v q) ^ ¬ r • The IB will help you by making the table the right size • Because we have three original propositions (p, q, r), we will have 23 = 8 rows below the header. Try the Lizzy Truth Table
You should be able to: • Say if something is/isn’t a proposition. (Tues.) • Negate propositions. (Tues.) • Use conjunctions (and, ^), disjunctions (at least one, v), exclusive disjunctions (either/or, v). (Wed.) • Say if a statement is a tautology, logical contradiction, or neither. (Thurs.) • Say if two statements are logically equivalent. (Thurs.) For Tomorrow’s Quiz
P. 540, #1, 2, 3, 4, 6, 8 • P. 542 # 1, 2, 3, 4, 5, 6 do a and b. If there is more than one sub question, do i & ii HW Check/ Time For HW