std:: strict_weak_order

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

The concept strict_weak_order<R, T, U> specifies that the relation R imposes a strict weak ordering on its arguments.

Semantic requirements

A relation r is a strict weak ordering if

• it is irreflexive: for all x , r ( x, x ) is false ;
• it is transitive: for all a , b and c , if r ( a, b ) and r ( b, c ) are both true then r ( a, c ) is true ;
• let e ( a, b ) be ! r ( a, b ) && ! r ( b, a ) , then e is transitive: e ( a, b ) && e ( b, c ) implies e ( a, c ) .

Under these conditions, it can be shown that e is an equivalence relation, and r induces a strict total ordering on the equivalence classes determined by e .

Notes

The distinction between relation and strict_weak_order is purely semantic.

References

See also

• LessThanComparable