English
The cusp orbits of 𝒢 are the quotient of the cusp-relations by the action of 𝒢: CuspOrbits(𝒢) = MulAction.orbitRel.Quotient 𝒢 (cusps_subMulAction 𝒢).
Русский
Образы cusp-орбит подгруппы 𝒢 получаются как фактор по отношению орбит под действием 𝒢 на cusp-ы.
LaTeX
$$$\\mathrm{CuspOrbits}(\\mathcal{G}) = \\mathrm{MulAction}.\\mathrm{orbitRel}.\\mathrm{ Quotient} \\; \\mathcal{G} (\\mathrm{cusps\\_subMulAction}(\\mathcal{G}))$$$
Lean4
/-- The type of cusp orbits of `𝒢`, i.e. orbits for the action of `𝒢` on its own cusps. -/
abbrev CuspOrbits (𝒢 : Subgroup (GL (Fin 2) ℝ)) :=
MulAction.orbitRel.Quotient 𝒢 (cusps_subMulAction 𝒢)