Lecture 006

Proof Writing

Direct Proofs: attempt to prove statement is itself true Indirect Proofs: prove the negation of the statement is false. (proofs by contradiction: AFSOC - assume for the sake of contradiction)

Universal Statements

Universal Statement: (\forall x \in S)P(x)

Set Containment Proofs: show A \subset B by showing (\forall a \in A)(a\in B)

Double Containment Proof:

(see example 6.3 on lecture note Here)

QED(\blacksquare): quod erat demonstrandum (proof is done)

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