most recent semester
lect05b
proofs; sets
Review a hw prob (proof by contra-positive: 1/x rational.).
Set:
- def'n. No order, no repetition.
Define explicitly, or as a rule (set-builder notation)
- common sets: φ, N, Z, Q, R, C; B, Sigma, Sigma*
intervals of real numbers: [a,b] (a,b)
eg [0,1]; (0,Infinity); [0,1).
- def'n 'subset'; equals. Proof A = B iff A⊆B, B⊆A.
- constructors (w/ Venn Diagrams)
union, intersect, complement, set-diff (R-Q; N-{0})
Examples: P=primes, O=odd, E=even.
E ∪ O = ??
E ∩ O = ??
P ∩ E = ?
P ∪ O = ?
...to be continued...
most recent semester
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