PROOF by CONTRADICTION DISCRETE MATHEMATICS YouTube Contradiction Math Symbol. Ⓡ or ⓟ or ⓒ. PROOF by CONTRADICTION DISCRETE MATHEMATICS YouTube Ⓡ or ⓟ or ⓒ. Ⓡ or ⓟ or ⓒ. Ⓡ or ⓟ or ⓒ.