A C++ comparator must be a strict weak ordering. The three properties of a strict weak ordering is asymmetry, irreflexivity, and transitivity.

Asymmetry means that if $$$a < b$$$, then $$$b \not<a$$$.

Irreflexivity means $$$a<a$$$ is false.

Transitivity means if $$$a<b$$$ and $$$b<c$$$ then $$$a<c$$$.

Your comparator contradicts all three.