_:b663913311 . _:b663913311 "Continuant fiat boundary doesn't have a closure axiom because the subclasses don't necessarily exhaust all possibilites. An example would be the mereological sum of two-dimensional continuant fiat boundary and a one dimensional continuant fiat boundary that doesn't overlap it. The situation is analogous to temporal and spatial regions."@en . _:b663913311 . _:b663913311 . _:b663913311 . _:b663913311 . _:b663913311 .