NAME

std::relation - std::relation

Synopsis

Defined in header <concepts>
template <class R, class T, class U>

concept relation = (1) (since C++20)
std::predicate<R, T, T> && std::predicate<R, U, U> &&

std::predicate<R, T, U> && std::predicate<R, U, T>;

The concept relation<R, T, U> specifies that R defines a binary relation over the
set of expressions whose type and value category are those encoded by either T or U.