Reference · Sets
rainbow.math.sets.inverse-unique-fiber
Two-sided set inverses provide unique witnesses in every target fiber.
set/inverse-on-has-unique-fibers
set/inverse-on-has-unique-fibers.{u, v} :
(A : Type u) (B : Type v) (forward : A → B) (backward : B → A) (source : set/Set A)
(target : set/Set B) (forward-maps : set/maps-to A B forward source target)
(backward-maps : set/maps-to B A backward target source)
(inverse-evidence : set/inverse-on A B backward forward source target) (value : B)
(target-member : target value)
→ proposition/unique-existence A (within)
where within := set/fiber-within A B forward source valueset/inverse-on-backward-in-fiber
set/inverse-on-backward-in-fiber.{u, v} :
(A : Type u) (B : Type v) (forward : A → B) (backward : B → A) (source : set/Set A)
(target : set/Set B) (backward-maps : set/maps-to B A backward target source)
(inverse-evidence : set/inverse-on A B backward forward source target) (value : B)
(target-member : target value)
→ set/fiber-within A B forward source value (backward value)set/inverse-on-fiber-member-equals-backward
set/inverse-on-fiber-member-equals-backward.{u, v} :
(A : Type u) (B : Type v) (forward : A → B) (backward : B → A) (source : set/Set A)
(target : set/Set B)
(inverse-evidence : set/inverse-on A B backward forward source target) (value : B)
(candidate : A)
(candidate-fiber : set/fiber-within A B forward source value candidate)
→ candidate = backward value= = equality/Eq
set/inverse-on-has-canonical-unique-fibers
set/inverse-on-has-canonical-unique-fibers.{u, v} :
(A : Type u) (B : Type v) (forward : A → B) (backward : B → A) (source : set/Set A)
(target : set/Set B) (backward-maps : set/maps-to B A backward target source)
(inverse-evidence : set/inverse-on A B backward forward source target) (value : B)
(target-member : target value)
→ proposition/conjunction (within) (∀ (other : A), ∀ (other-evidence : set/fiber-within A B forward source value other), other = backward value)
where within := set/fiber-within A B forward source value (backward value)= = equality/Eq