Propositional Logic Flashcards
1
Q
Proposition
A
A proposition is something the content of which may or may not be the case, a claim which is either true or false.
2
Q
When do we call a proposition true or false?
A
We call a proposition true if its content is the case and false if it is not.
3
Q
And
A
True if: both true
4
Q
Or
A
v
True if: one of the two or both true.
5
Q
If…then
A
->
True if: the second one is true or the first one is false.
6
Q
Not
A
¬
True if: False
7
Q
Then and only then
A
<->
True if: both true or both false
8
Q
tautology
A
a statement which is always true (irrespective of the truth values of the propositional variables).
9
Q
contradiction or absurdity
A
a proposition which is always false, such as ‘it is snowing and it is not snowing’
10
Q
a contingency
A
a proposition which is sometimes true and sometimes false.
