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agda-spa/lean/Spa/Lattice/IterProd.lean
Danila Fedorin e2df847139 Adopt lemma as the default keyword
Convert every theorem to lemma (mathlib's default) except the headline results a
reader of each module seeks out: analyze_correct (Forward/Sign/Constant),
aFix_eq/aFix_le (Fixedpoint), trace (Language), and Stmt.cfg_sufficient
(Language/Properties). lemma and theorem are interchangeable keywords, so no
references change.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
2026-06-25 14:08:10 -05:00

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import Spa.Lattice.Prod
import Spa.Lattice.Unit
namespace Spa
universe u
def IterProd (A B : Type u) : Type u
| 0 => B
| k + 1 => A × IterProd A B k
namespace IterProd
variable {A B : Type u}
instance lattice [Lattice A] [Lattice B] :
k, Lattice (IterProd A B k)
| 0 => inferInstanceAs (Lattice B)
| k + 1 => @Prod.instLattice A (IterProd A B k) _ (lattice k)
instance decidableEq [DecidableEq A] [DecidableEq B] :
k, DecidableEq (IterProd A B k)
| 0 => inferInstanceAs (DecidableEq B)
| k + 1 => @instDecidableEqProd A (IterProd A B k) _ (decidableEq k)
def build (a : A) (b : B) : (k : ) IterProd A B k
| 0 => b
| k + 1 => (a, build a b k)
variable [Lattice A] [Lattice B]
def fixedHeight [FiniteHeightLattice A] [FiniteHeightLattice B] :
k, FiniteHeightLattice (IterProd A B k)
| 0 => inferInstanceAs (FiniteHeightLattice B)
| k + 1 => @Spa.prod A (IterProd A B k) _ (lattice k) _ (fixedHeight k)
instance finiteHeight [FiniteHeightLattice A] [FiniteHeightLattice B] (k : ) :
FiniteHeightLattice (IterProd A B k) := fixedHeight k
lemma bot_fixedHeight [FiniteHeightLattice A] [FiniteHeightLattice B] :
k, (fixedHeight (A := A) (B := B) k).bot = build ( : A) ( : B) k
| 0 => rfl
| k + 1 => by
show (( : A), (fixedHeight (A := A) (B := B) k).bot)
= (( : A), build ( : A) ( : B) k)
rw [bot_fixedHeight k]
end IterProd
end Spa