CO2412: Computational Thinking
Lecture 17
Propositional Logic
1. What is Propositional Logic?
o Propositional logic is used to establish the validity of arguments. It
provides rules that allow us to judge whether an argument is sound
or unsound, helping us determine whether a conclusion drawn from
stated premises is valid.
2. Propositions
o A proposition is a statement that is either true or false.
o Examples:
o 6 < 24 (True)
o 3 + 2 = 4 (False)
o "Tomorrow is my birthday" (Dependent on context)
3. Non-Propositional Statements
o Questions and exclamations are not propositions because they do
not equate to true or false.
o Examples:
o "Keep off the grass!" (Exclamation)
o "What time is it?" (Question)
Compound Propositions and Connectives
1. Compound Propositions
o Simple propositions can be combined using connectives to form
compound propositions.
o Negation: Reverses the truth value of a proposition. For example, if
p is true, then ¬p (not p) is false.
Lecture 17
Propositional Logic
1. What is Propositional Logic?
o Propositional logic is used to establish the validity of arguments. It
provides rules that allow us to judge whether an argument is sound
or unsound, helping us determine whether a conclusion drawn from
stated premises is valid.
2. Propositions
o A proposition is a statement that is either true or false.
o Examples:
o 6 < 24 (True)
o 3 + 2 = 4 (False)
o "Tomorrow is my birthday" (Dependent on context)
3. Non-Propositional Statements
o Questions and exclamations are not propositions because they do
not equate to true or false.
o Examples:
o "Keep off the grass!" (Exclamation)
o "What time is it?" (Question)
Compound Propositions and Connectives
1. Compound Propositions
o Simple propositions can be combined using connectives to form
compound propositions.
o Negation: Reverses the truth value of a proposition. For example, if
p is true, then ¬p (not p) is false.
