Overlappedby

Overlappedby is a binary temporal relation used in interval algebra to indicate that one time interval is overlapped by another. It is the inverse of the overlaps relation: overlappedby(A, B) holds exactly when overlaps(B, A) holds.

In formal terms, if intervals are represented as [start, end], overlappedby(A, B) is true when B overlaps A. A common way to express this is: B1 < A1 < B2 < A2, where B1 and B2 are the start and end of B, and A1 and A2 are the start and end of A. This means B starts before A, B ends after A starts, but B ends before A ends.

In the context of Allen’s interval algebra, overlappedby is the inverse of the overlaps relation. It is not symmetric; for two intervals A and B, A overlappedby B does not imply B overlappedby A, but it does imply B overlaps A.

Applications of overlappedby appear in temporal reasoning, scheduling, event sequencing, natural language processing, and temporal databases. Data models and knowledge graphs may encode this relation to reason about the ordering and intersection of events or tasks, enabling constraints like “Event A is overlapped by Event B.”

Notational variants include overlappedBy in camelCase or overlapped_by in snake_case when used in programming, while the natural-language form remains “overlapped by.” Related concepts include overlaps, before, after, meets (and their inverses), and other relations from Allen’s interval algebra.