theorem instTemporalRegionAtToParent
theorem instTemporalRegionAtToParent: ∀ (x t : Type) [TemporalRegion.At x t], Occurrent.At x t
theorem instTemporalRegionAtToParent
theorem instTemporalRegionAtToParent: ∀ (x t : Type) [TemporalRegion.At x t], Occurrent.At x t