English
The dual of a family of sets under a sUnion equals the infimum of duals of the sets.
Русский
Дуал объединения множества по подмножествах (sUnion) равен наименьшему дуалам подмножеств.
LaTeX
$$dual p (⋃₀ S) = sInf (dual p '' S)$$
Lean4
/-- The inner dual cone of a singleton is given by the preimage of the positive cone under the
linear map `p x`. -/
theorem dual_singleton [IsTopologicalRing R] [OrderClosedTopology R] (x : M) :
dual p { x } = (positive R R).comap (p.toContPerfPair x) := by ext; simp