std::strict_weak_order

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strict_weak_order (C++20)

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Defined in header`<concepts>`
template<class R,class T,class U> concept strict_weak_order=std::relation<R, T, U>;		(since C++20)

The conceptstrict_weak_order<R, T, U> specifies that therelationR imposes a strict weak ordering on its arguments.

[edit]Semantic requirements

A relationr is a strict weak ordering if

it is irreflexive: for allx,r(x, x) isfalse;
it is transitive: for alla,b andc, ifr(a, b) andr(b, c) are bothtrue thenr(a, c) istrue;
lete(a, b) be!r(a, b)&&!r(b, a), thene is transitive:e(a, b)&& e(b, c) impliese(a, c).

Under these conditions, it can be shown thate is an equivalence relation, andr induces a strict total ordering on the equivalence classes determined bye.