Orbits of group actions

Content created by Fredrik Bakke, Jonathan Prieto-Cubides and Egbert Rijke.

Created on 2022-03-17.
Last modified on 2023-03-13.

module group-theory.orbits-group-actions where
Imports 
open import foundation.dependent-pair-types
open import foundation.identity-types
open import foundation.universe-levels

open import group-theory.group-actions
open import group-theory.groups

Idea

The orbit of an element x in a G-set X is the set of elements of the form gx.

Definition

module _
  {l1 l2 : Level} (G : Group l1) (X : Abstract-Group-Action G l2)
  where

  hom-orbit-Abstract-Group-Action :
    (x y : type-Abstract-Group-Action G X) → UU (l1 ⊔ l2)
  hom-orbit-Abstract-Group-Action x y =
    Σ (type-Group G) (λ g → Id (mul-Abstract-Group-Action G X g x) y)

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