mathlib

8a097f13 - feat(ring_theory/ideal_operations): inj_iff_trivial_ker for ring homomorphisms (#951)

feat(ring_theory/ideal_operations): inj_iff_trivial_ker for ring homomorphisms (#951) * feat(ring_theory/ideal_operations): inj_iff_trivial_ker for ring homomorphisms * Update subgroup.lean * Update ideal_operations.lean