English
If a and b are equivalent under ≤, then CovBy with c from the right is preserved: c ⋖ a iff c ⋖ b.
Русский
Если a и b эквивалентны относительно ≤, тогда c ⋖ a эквивалентно c ⋖ b.
LaTeX
$$$ (\\text{AntisymmRel}(\\le)\\ a\\ b) \\Rightarrow (\\,c \\,⋖\\, a \\iff c \\,⋖\\, b) $$$
Lean4
theorem covBy_congr_right (hab : AntisymmRel (· ≤ ·) a b) : c ⋖ a ↔ c ⋖ b :=
⟨fun h => h.trans_antisymmRel hab, fun h => h.trans_antisymmRel hab.symm⟩