Anglo-American property law allows for ownership to be divided among multiple owners over time. The law of future interests and conveyances that create them are notoriously complicated. They follow rigid syntactic conventions and are governed by an intricate body of interlocking doctrines that determine their legal effect. These doctrines have been codified, but only in informal and ambiguous ways.
Littleton is an interpreter that automatically parses conveyances and displays the resulting state of title. It covers most of the kinds of interests covered in a typical first-year Property course, can evaluate the consequences of events, apply doctrines like vesting, and solve basic Rule Against Perpetuities problems.