Nontrivial

нетривиальный

Англо-русский научно-технический словарь

Nontrivial

Requiring real thought or significant computing power. Often used as an understated way of saying that a problem is quite difficult or impractical, or even entirely unsolvable ("Proving P=NP is nontrivial"). The preferred emphatic form is "decidedly nontrivial". See uninteresting, interesting.

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