nonconstructive
Adjective
Meaning
Not constructive.
Not involving construction.
(mathematics) That proves the existence of something without demonstrating a method of construction.
Source: en.wiktionary.orgSynonyms
Antonyms
Examples
The relationship between provability in classical (or nonconstructive) systems and provability in intuitionistic (or constructive, respectively) systems is of particular interest.
This nonconstructive proof that not all real numbers are algebraic was first published by Georg Cantor in his 1874 paper " On a Property of the Collection of All Real Algebraic Numbers ".
In constructive mathematics As discussed above, in ZFC, the axiom of choice is able to provide " nonconstructive proofs " in which the existence of an object is proved although no explicit example is constructed.
The motivation for accepting these seemingly nonconstructive principles is the intuitionistic understanding of the proof that "for each real number x there is a real number y such that R(x,y) holds".
Though nearly all modern mathematicians consider nonconstructive methods just as sound as constructive ones, Euclid's constructive proofs often supplanted fallacious nonconstructive ones—e.
While the ability to make such a choice is considered obvious by some, since each set in the collection is nonempty, the lack of a general, concrete rule by which the choice can be made renders the axiom nonconstructive.