Chapter 3 - Semantics

Question 1

a formula is called logically true or a ________ just incase it is true on every truth-value assignment

Answer 1

tautology

Question 2

a formula is called a ___________ just in case it is false on every truth-value assignment

Answer 2

contradictory

Question 3

a formula is called a ___________ just in case it is true on some truth-value assignment, and false on others

Answer 3

contingent

Question 4

The conclusion of an argument is a ________ _________ of its premises if and only if any truth-value assignment that makes all the premises true also makes the conclusion true.

Answer 4

logical consequence

Question 5

An argument is _______ if and only if its conclusion is a logical consequence of its premises.

Answer 5

valid

Question 6

An argument is ______ in case it is not valid, that is, if there is some truth-value assignment that makes the premises true, but the conclusion false.

Answer 6

invalid

Question 7

A truth-value assignment that makes the premises of an argument true and its conclusion false is called a _________ to the argument.

Answer 7

counterexample