Correspondence theorem (rings): Let RR be a ring, let I◃RI\triangleleft R be an , and let π:R→R/I\pi:R\to R/I be the quotient map. Then the assignment

J ⟼ J/IJ\ \longmapsto\ J/I

is an inclusion-preserving bijection between ideals JJ of RR with I⊆JI\subseteq J and ideals of the R/IR/I. The inverse bijection sends an ideal K◃R/IK\triangleleft R/I to the π−1(K)\pi^{-1}(K).

Remarks

Under this correspondence, (and likewise in the commutative case) correspond to prime (respectively maximal) ideals containing II.