semiurn

A semiurn is a type of urn in probability and statistics, often used in problems involving the selection of items where the probability of drawing an item of a certain type changes with each draw, but not in a way that implies removal from the urn. This contrasts with a standard urn model where items are either replaced or not replaced. In a semiurn scenario, the composition of the urn might be thought of as being updated or modified between draws in a predetermined manner, or perhaps influenced by the outcomes of previous draws, but the physical items themselves are not necessarily removed or returned in the traditional sense. The term "semiurn" is not as universally standardized as terms like "urn" or "Laplace's urn." It may arise in specific contexts or in the formulation of custom probability problems. The key characteristic is a dynamic or altered probability space for subsequent events that isn't simply a direct consequence of removing or replacing an item. This could involve concepts like a changing probability of success on each trial, where the underlying process is analogized to an urn's contents, but the mechanics differ from basic urn models.