M1 Topic 2: Propositions Flashcards
A declarative statement which is true or false, but not both. Lowercase letters such as p, q, r, and s are used to represent simple propositions
Proposition (or statement)
The study of how simple propositions can come together to make more complicated propositions
Propositional logic
The attribute assigned to a proposition depending on its truthfulness or falsehood, which in classical logic has only two possible values (true or false)
Truth value
In Propositional Logic, we assume a collection of simple or atomic propositions are given:
p, q, r, s, t, ….
Then we form compound propositions by using logical connectives (logical operators) to form ______
propositional “molecules”
A mathematical table showing how truth or falsity of a proposition varies with that of its components
truth table
Interpreted intuitively as being true when p is false and false when p is true
Negation (¬p)
What happens when we use the word “and” in English. If one is false, then the compound statement is false as well.
Conjunction (p∧q)
The use of “or”. It is true when at least one of the two propositions is true.
Disjunction (p∨q)
Usage of “if, then” or “implies”. p → q is false only if p is true while q is false
Conditional/Implication (p→q)
p is called the ______ (or antecedent or premise) under Conditional/Implication
hypothesis
q is called the ______ (or consequence) under Conditional/Implication
conclusion
Ways to express the conditional statement p→q:
- If p then q
- p implies q
- If p, q
- p only if q
- p is sufficient for q
Some of the ways reverse the order of p and q but have the same connotation i.e. p→q:
- q if p
- q whenever p
- q is necessary for p
Is read as “p if and only if q”. For p↔q to be true, p and q must have the same truth values. Otherwise, p↔q is false
Bi-conditional/Double Implication (p↔q)