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Mathlib.Deprecated.RingHom

Additional lemmas about homomorphisms of semirings and rings #

These lemmas were in Mathlib/Algebra/Hom/Ring/Defs.lean and have now been deprecated.

@[deprecated "Use range_eq_singleton_iff and codomain_trivial_iff_range_trivial" (since := "2025-06-09")]
theorem RingHom.codomain_trivial_iff_range_eq_singleton_zero {α : Type u_1} {β : Type u_2} {x✝ : NonAssocSemiring α} {x✝¹ : NonAssocSemiring β} (f : α →+* β) :
0 = 1 Set.range f = {0}

f : α →+* β has a trivial codomain iff its range is {0}.

@[deprecated map_dvd (since := "2025-06-09")]
theorem RingHom.map_dvd {α : Type u_1} {β : Type u_2} [Semiring α] [Semiring β] (f : α →+* β) {a b : α} :
a bf a f b