diff --git a/src/topology/uniform_space/basic.lean b/src/topology/uniform_space/basic.lean index 0a53ed4548222..ae28ce297ba17 100644 --- a/src/topology/uniform_space/basic.lean +++ b/src/topology/uniform_space/basic.lean @@ -195,12 +195,11 @@ lemma symmetric_rel.mk_mem_comm {V : set (α × α)} (hV : symmetric_rel V) {x y (x, y) ∈ V ↔ (y, x) ∈ V := set.ext_iff.1 hV (y, x) -lemma symmetric_rel_inter {U V : set (α × α)} (hU : symmetric_rel U) (hV : symmetric_rel V) : +lemma symmetric_rel.eq {U : set (α × α)} (hU : symmetric_rel U) : prod.swap ⁻¹' U = U := hU + +lemma symmetric_rel.inter {U V : set (α × α)} (hU : symmetric_rel U) (hV : symmetric_rel V) : symmetric_rel (U ∩ V) := -begin - unfold symmetric_rel at *, - rw [preimage_inter, hU, hV], -end +by rw [symmetric_rel, preimage_inter, hU.eq, hV.eq] /-- This core description of a uniform space is outside of the type class hierarchy. It is useful for constructions of uniform spaces, when the topology is derived from the uniform space. -/ @@ -658,7 +657,7 @@ begin rw nhds_prod_eq, apply (has_basis_nhds x).prod' (has_basis_nhds y), rintro U V ⟨U_in, U_symm⟩ ⟨V_in, V_symm⟩, - exact ⟨U ∩ V, ⟨(𝓤 α).inter_sets U_in V_in, symmetric_rel_inter U_symm V_symm⟩, + exact ⟨U ∩ V, ⟨(𝓤 α).inter_sets U_in V_in, U_symm.inter V_symm⟩, ball_inter_left x U V, ball_inter_right y U V⟩, end