modus tollens

(redirected from Proof by contrapositive)
Related to Proof by contrapositive: Proof by contradiction, Proof by induction

modus tollens

(ˈməʊdəs ˈtɒlˌɛnz)
n
(Logic) logic the principle that whenever a conditional statement and the negation of its consequent are given to be true, the negation of its antecedent may be validly inferred, as in if it's Tuesday this must be Belgium and this isn't Belgium so it's not Tuesday
[literally: mood that denies]
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014
References in periodicals archive ?
Thus, the proof by contrapositive of the "only if" part is complete and so is the proof of the entire statement.
2 [??] 3 (Proof by contrapositive: [logical not]3 [??] [logical not] 2.) Let n [greater than or equal to] 3 and i, j, k distinct indices so that i < j, [a.sub.jk] = 1 and [a.sub.ik] = 0.