[DEFINE] LOGIC: Terminologies Flashcards
Logic
a system of reasoning that allows inferences to be drawn from facts.
Proposition
a declarative sentence that is either true or false, but not both.
Conjunction
‘AND’ statement in mathematics. A conjunction of two statements is true only when both statements are true.
Disjunction
“OR” statement in mathematics. A disjunction is false if and only if both statements are false; otherwise it is true.
Negation
“NOT” statement in mathematics. It is a statement with the opposite truth value. If a statement is true, then its negation is false, and vice versa.
Conditional (or implication)
a logical compound statement in which p implies q. The statement is only false when p is true but q is false.
Biconditional
True when both have the same truth value.
Exclusive-or
The statement is only true if it has differnent truth values. P and q cannot be the same
EX: I am a dog or I am a cat
Truth Values of proposition
The truth value of a proposition is a determination of whether the proposition is true (T) or false (F). In classical logic, a proposition can only have one of these two truth values.
Proposition: “The sun rises in the east.”
This statement is true. Hence, its truth value is T (true).
Conditional Propositions
an “if-then” expression. It is false only when p is true and q is false, and is true in all other situations.
Converse of p-q
A conditional proposition in which the statement “p implies q” is “q implies p”. It is created by swapping the order of the hypothesis and conclusion.
Inverse of p-q
A conditional proposition in which the statement “p implies q” is “not p implies not q.” The order of the hypothesis and the conclusion remains the same, but they are both negated.
Contrapositive
A conditional proposition in which the statement “p implies q” is “not q implies not p.” It is formed by negating and swapping the hypothesis and the conclusion
Tautology
a proposition that is always true
Contradiction
a proposition that is always false
Contingency
It is neither a tautology nor a contradiction. In other words, it is a proposition that is neither true nor false.
Proof
a logical argument that shows a mathematical statement is true.
Premises
AKA the cause. a statement that is assumed to be true and is used as the basis for an argument.
Conclusion
AKA the effect. a statement that is reached by applying logical rules to a set of premises.
Number Theory
branch of pure mathematics mainly to study natural numbers and integers.
Counting
a subset of whole numbers that do not include zero
Whole
a subset of whole numbers that includes the number zero
Integers
a whole number (not a fractional number) that can be positive, negative, or zero.
Rational Numbers
are numbers that can be written as a fraction or a ratio.
Irrational Numbers
are numbers that can’t be written as a fraction or ratio.