contacthas

Contacthas is a term used in data modeling to denote the existence of an interaction between two entities within a defined period. It is commonly used in epidemiology, social network analysis, and event-driven simulations to reason about contact-based relationships.

Semantics: contactHas(x, y) represents that x has had contact with y during the observation window. The relation may be symmetric if contact is defined as mutual, or asymmetric if direction matters (for example, contact initiated by x toward y). Time bounds can be explicit, and the exact interpretation may vary by model or domain.

In practice, contacthas is implemented as a predicate or as a database query. In a relational schema, a table of interactions with columns such as person_a, person_b, timestamp can be queried to determine whether contactHas(a, b) holds for a given window. In graph databases, it may be represented by a binary edge labeled "CONTACT_HAS" between vertex nodes, possibly with properties such as time, duration, and context.

Applications: contacthas supports contact tracing, exposure notification, and dynamic simulations where agents interact. It is commonly used in conjunction with additional predicates, such as contactHasWithin(a, b, t1, t2) or contactDuration(a, b), to capture more granular interaction details.

See also: contact tracing, relation algebra, predicate logic, graph databases.