English
There exists a lattice structure on seminorms: the infimum of two seminorms is defined by the convolution (p ⊓ q)(x) = inf_u (p(u) + q(x-u)).
Русский
Существует решетка над семинормами: инфимум двух семинорм задаётся свёрткой (p ⊓ q)(x) = inf_u (p(u) + q(x-u)).
LaTeX
$$$(p \inf q)(x) = \inf_{u \in E} \left( p(u) + q(x-u) \right)$$$
Lean4
/-- Auxiliary lemma to show that the infimum of seminorms is well-defined. -/
theorem bddBelow_range_add : BddBelow (range fun u => p u + q (x - u)) :=
⟨0, by
rintro _ ⟨x, rfl⟩
dsimp; positivity⟩