Bezpośredni dowód

Direct proof We suppose, that all assumptions of a theorem are true
( p is true), and then we infer, that the conclusion is true
( q is true).
Example:
Prove the theorem: ”If m and n are odd, then m · n is
odd.”
Proof: m, n - odd, so: m = 2 k 1 + 1, n = 2 k 2 + 1. So: m · n = (2 k 1+1)(2 k 2+1) = 2(2 k 1 k 2+ k 1+ k 2)+1 = 2 k +1
- odd.
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