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fix: add a missing where to correct a vacuous class #431

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fix: add a missing where to correct a vacuous class #431

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1f49e26
fix: add a missing `where` to correct a vacuous class
eric-wieser Mar 17, 2026
baa506c
another one
eric-wieser Mar 17, 2026
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17 changes: 8 additions & 9 deletions Cslib/Foundations/Semantics/LTS/Basic.lean
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Original file line number Diff line number Diff line change
Expand Up @@ -641,8 +641,7 @@ theorem LTS.mem_foldl_setImage (lts : LTS State Label) :
exact LTS.mem_setImageMultistep

/-- An lts is image-finite if all images of its states are finite. -/
@[scoped grind]
class LTS.ImageFinite [image_finite : ∀ s μ, Finite (lts.image s μ)]
abbrev LTS.ImageFinite := ∀ s μ, Finite (lts.image s μ)

/-- In a deterministic LTS, if a state has a `μ`-derivative, then it can have no other
`μ`-derivative. -/
Expand Down Expand Up @@ -674,11 +673,11 @@ instance [lts.Deterministic] (s : State) (μ : Label) : Finite (lts.image s μ)
apply Set.finite_empty

/-- Every deterministic LTS is also image-finite. -/
instance LTS.deterministic_imageFinite [lts.Deterministic] : lts.ImageFinite := {}
instance LTS.deterministic_imageFinite [lts.Deterministic] : lts.ImageFinite := inferInstance

/-- Every finite-state LTS is also image-finite. -/
@[scoped grind .]
instance LTS.finiteState_imageFinite [Finite State] : lts.ImageFinite := {}
instance LTS.finiteState_imageFinite [Finite State] : lts.ImageFinite := inferInstance

/-- A state has an outgoing label `μ` if it has a `μ`-derivative. -/
def LTS.HasOutLabel (s : State) (μ : Label) : Prop :=
Expand All @@ -689,14 +688,14 @@ def LTS.outgoingLabels (s : State) := { μ | lts.HasOutLabel s μ }

/-- An LTS is finitely branching if it is image-finite and all states have finite sets of
outgoing labels. -/
class LTS.FinitelyBranching
[image_finite : ∀ s μ, Finite (lts.image s μ)]
class LTS.FinitelyBranching where
[image_finite : lts.ImageFinite]
[finite_state : ∀ s, Finite (lts.outgoingLabels s)]

attribute [instance] LTS.FinitelyBranching.image_finite LTS.FinitelyBranching.finite_state

/-- Every LTS with finite types for states and labels is also finitely branching. -/
@[scoped grind .]
instance LTS.finiteState_finitelyBranching [Finite State] [Finite Label] : lts.FinitelyBranching :=
{}
instance LTS.FinitelyBranching.of_finite [Finite State] [Finite Label] : lts.FinitelyBranching where

/-- An LTS is acyclic if there are no infinite multistep transitions. -/
class LTS.Acyclic (lts : LTS State Label) where
Expand Down
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