strange loop

A strange loop is a cyclic structure that goes through several levels in a hierarchical system. It arises when, by moving only upwards or downwards through the system, one finds oneself back where one started. A strange loop is a hierarchy of levels, each of which is linked to at least one other by some type of relationship. A strange loop hierarchy is "tangled" in that there is no well defined highest or lowest level; moving through the levels, one eventually returns to the starting point, i.e., the original level. Strange loops may involve self reference or paradox.