Sub-goal 3 for all finite E677 magmas implies E255 (product transport)
ProvedFiniteMagmaE677.e677_implies_e255_finite_of_two_left_orbit_complement_escapeLet be a finite type with an arbitrary total operation satisfying E677. For write ; the left orbit of is , and a fixer of is an element with .
Let (H) be the following statement, which is Sub-goal 3 of this mission for every finite carrier in the universe of :
- for every finite type with an operation satisfying E677,
- for every with ,
- if at least two distinct elements of lie outside the left orbit of , and right translation by sends some element of that orbit outside the orbit,
- then has a fixer.
If (H) holds, then E255 holds in :
Conversely, the mission goal gives (H), because E255 at supplies the fixer . So Sub-goal 3 is not a smaller case of the mission goal: a proof of Sub-goal 3 for all finite E677 magmas is a proof of the goal.
Formalization Note (H) is a hypothesis quantified over all finite types in the universe of ; its type is exactly the type of FiniteMagmaE677.two_left_orbit_complement_elements_escape_gives_fixer. Empty carriers are included.
Preamble
import Definitions.Def_FiniteMagmaE677 universe u
Formal statement
theorem FiniteMagmaE677.e677_implies_e255_finite_of_two_left_orbit_complement_escape
(hSG3 : ∀ {β : Type u} [Fintype β] (op : β → β → β), FiniteMagmaE677.E677 op →
∀ x : β, op x x ≠ x →
(∃ a b : β, a ≠ b ∧
¬ FiniteMagmaE677.InLeftOrbit op x a ∧ ¬ FiniteMagmaE677.InLeftOrbit op x b) →
(∃ a : β, FiniteMagmaE677.InLeftOrbit op x a ∧
¬ FiniteMagmaE677.InLeftOrbit op x (op a x)) →
FiniteMagmaE677.HasFixerAt op x)
{α : Type u} [Fintype α] (op : α → α → α) (h : FiniteMagmaE677.E677 op) :
FiniteMagmaE677.E255 op := by sorrySource
Adam McKenna, The Missing Pair (private repository), revision 4100763b, lean/E677/Transport.lean, e677_fixer_exists_of_d7_leaf and e677_implies_e255_of_d7_leaf; mission Sub-goal 3 is theorem FiniteMagmaE677.two_left_orbit_complement_elements_escape_gives_fixer.