 In this model, the outcome of revising \([K]\) by \([p]\) should be the intersection of \([p]\) with the narrowest sphere around \([K]\) that has a non-empty intersection with \([p]\), as in Diagram 2. This construction was invented by Adam Grove (1988), who also proved that such sphere-based revision corresponds exactly to transitively relational partial meet revision. It follows that it also corresponds exactly to entrenchment-based revision.