Lattice operations on finsets #
This file is concerned with folding binary lattice operations over finsets.
For the special case of maximum and minimum of a finset, see Max.lean.
See also Mathlib/Order/CompleteLattice/Finset.lean
, which is instead concerned with how big
lattice or set operations behave when indexed by a finset.
sup #
Supremum of a finite set: sup {a, b, c} f = f a ⊔ f b ⊔ f c
Equations
- s.sup f = Finset.fold (fun (x1 x2 : α) => x1 ⊔ x2) ⊥ f s
Instances For
Alias of the reverse direction of Finset.sup_le_iff
.
See also Finset.product_biUnion
.
Computing sup
in a subtype (closed under sup
) is the same as computing it in α
.
inf #
Infimum of a finite set: inf {a, b, c} f = f a ⊓ f b ⊓ f c
Equations
- s.inf f = Finset.fold (fun (x1 x2 : α) => x1 ⊓ x2) ⊤ f s
Instances For
Alias of the reverse direction of Finset.le_inf_iff
.
Computing inf
in a subtype (closed under inf
) is the same as computing it in α
.
Given nonempty finset s
then s.sup' H f
is the supremum of its image under f
in (possibly
unbounded) join-semilattice α
, where H
is a proof of nonemptiness. If α
has a bottom element
you may instead use Finset.sup
which does not require s
nonempty.
Instances For
Alias of the reverse direction of Finset.sup'_le_iff
.
See also Finset.sup'_prodMap
.
See also Finset.prodMk_sup'_sup'
.
To rewrite from right to left, use Finset.sup'_comp_eq_image
.
A version of Finset.sup'_image
with LHS and RHS reversed.
Also, this lemma assumes that s
is nonempty instead of assuming that its image is nonempty.
To rewrite from right to left, use Finset.sup'_comp_eq_map
.
A version of Finset.sup'_map
with LHS and RHS reversed.
Also, this lemma assumes that s
is nonempty instead of assuming that its image is nonempty.
Given nonempty finset s
then s.inf' H f
is the infimum of its image under f
in (possibly
unbounded) meet-semilattice α
, where H
is a proof of nonemptiness. If α
has a top element you
may instead use Finset.inf
which does not require s
nonempty.
Instances For
See also Finset.inf'_prodMap
.
See also Finset.prodMk_inf'_inf'
.
To rewrite from right to left, use Finset.inf'_comp_eq_image
.
A version of Finset.inf'_image
with LHS and RHS reversed.
Also, this lemma assumes that s
is nonempty instead of assuming that its image is nonempty.
To rewrite from right to left, use Finset.inf'_comp_eq_map
.
A version of Finset.inf'_map
with LHS and RHS reversed.
Also, this lemma assumes that s
is nonempty instead of assuming that its image is nonempty.