Week 1 Flashcards
What is the definition of a statement in mathematics?
A statement is a sentence that is always true or always false.
What is an implication statement?
A implies B. If A is true then B is true, otherwise B is false. A->B
What is a compound statement?
A combination of two or more statements to communicate a larger statement.
What is the double negation property of statements?
Neg(Neg A) = A
What are the De Morgan Laws of statements?
Neg(A and B) = Neg A or Neg B
Neg(A or B) = Neg A and Neg B
What are the distributivity laws of statements?
A and (B or C) = (A and B) or (A and C)
A or (B and C) = (A or B) and (A or C)
What are contrapositive statements?
A -> B = neg(B) -> neg(A)
What are converse statements?
A -> B = B -> A
What is equivalence as double implication?
(A = B) = (A -> B) and (B -> A)
What is a direct proof?
Using a logical sequence of statements to show a statement is true/false. Use both maths and sentences.
What is a proof by contraposition?
Prove that A implies B by proving neg B implies neg A.
What is a proof by contradiction?
Start by assuming the opposite of the statement is true. Work through proving that the opposite is true until you get to a contradiction.
What is the definition of an even number?
n = 2a where a is an integer
What is the definition of an odd number?
n = 2a + 1 where a is an integer