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feat(Semantics/Events): isPunctual/isDurative; Basic namespace-Event block #33

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May 30, 2026
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feat(Semantics/Events): isPunctual/isDurative; Basic namespace-Event block #33

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24 changes: 24 additions & 0 deletions Linglib/Semantics/Events/Basic.lean
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Expand Up @@ -50,6 +50,30 @@ theorem isState_iff_not_isAction {Time : Type*} [LinearOrder Time] (e : Event Ti
simp only [Event.isAction, Event.isState]
cases e.sort <;> decide

/-! ### Duration predicates -/

/-- Is this event punctual (instantaneous)? Its runtime is a single point.
The temporal-extent counterpart of the dynamicity sort; derived from the
runtime via `Interval.IsPoint`. -/
def Event.isPunctual {Time : Type*} [LinearOrder Time] (e : Event Time) : Prop :=
e.τ.IsPoint

/-- Is this event durative (temporally extended)? -/
def Event.isDurative {Time : Type*} [LinearOrder Time] (e : Event Time) : Prop :=
¬ e.isPunctual

instance {Time : Type*} [LinearOrder Time] :
DecidablePred (Event.isPunctual (Time := Time)) :=
fun e => by unfold Event.isPunctual Interval.IsPoint; infer_instance

instance {Time : Type*} [LinearOrder Time] :
DecidablePred (Event.isDurative (Time := Time)) :=
fun e => by unfold Event.isDurative; infer_instance

/-- `isDurative` and `isPunctual` are complementary. -/
theorem isDurative_iff_not_isPunctual {Time : Type*} [LinearOrder Time] (e : Event Time) :
e.isDurative ↔ ¬ e.isPunctual := Iff.rfl

/-! ### Concrete examples (ℤ-time events) -/

/-- Example: a running event from time 1 to 5. -/
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