The Rees congruence of a Two-Sided Monoid Ideal I ⊆ M 𝐼 𝑀 I\subseteq M is the Monoid Congruence ρ(x,y):=(x=y)∨(x∈I∧y∈I)assign𝜌𝑥𝑦𝑥𝑦𝑥𝐼𝑦𝐼\par\rho(x,y):=(x=y)\lor(x\in I\land y\in I)
ρ(x,y):=(x=y)∨(x∈I∧y∈I)assign𝜌𝑥𝑦𝑥𝑦𝑥𝐼𝑦𝐼\par\rho(x,y):=(x=y)\lor(x\in I\land y\in I)