theorem BFO.instCoeFiatSurfaceContinuantFiatBoundary._proof_1
theorem BFO.instCoeFiatSurfaceContinuantFiatBoundary._proof_1: ∀ (v : j12bzjgj.BFO.FiatSurface), j12bzjgj.BFO.ContinuantFiatBoundary.Is (Subtype.val v)
theorem BFO.instCoeFiatSurfaceContinuantFiatBoundary._proof_1
theorem BFO.instCoeFiatSurfaceContinuantFiatBoundary._proof_1: ∀ (v : j12bzjgj.BFO.FiatSurface), j12bzjgj.BFO.ContinuantFiatBoundary.Is (Subtype.val v)