instant is before https://www.commoncoreontologies.org/TimeOntology 'instant is before' is a primitive relationship. Informally, a temporal instant t1 is before some temporal instant t2 if and only if t1 precedes t2. A temporal instant t1 (a instance of a zero-dimensional temporal region) is before another temporal instant t2 iff there exists some instance of a temporal interval ti1 such that t1 is the starting instant of ti1 and t2 is the ending instant of ti1. J. F. Allen and J. A. G. M. Koomen. Planning using a temporal world model. In Proceedings of the 8th International Joint Conference on Artificial Intelligence (IJCAI-1983) pages 741–747. Available at: https://www.ijcai.org/Proceedings/83-2/Papers/036.pdf zero-dimensional temporal region