English
An element s belongs to M.stepSet S a if and only if there exists t in S such that s ∈ εClosure(M.step t a).
Русский
s ∈ M.stepSet S a тогда и только тогда, когда существует t ∈ S с s ∈ εClosure(M.step t a).
LaTeX
$$$s \in M.stepSet S a \Leftrightarrow \exists t \in S, s \in M.\\varepsilonClosure( M.\\step t a )$$$
Lean4
@[simp]
theorem mem_stepSet_iff : s ∈ M.stepSet S a ↔ ∃ t ∈ S, s ∈ M.εClosure (M.step t a) := by
simp_rw [stepSet, mem_iUnion₂, exists_prop]