Glossary

Relation

A relation is a set of ordered pairs over a set of entities, events, or concepts E -- formally, a subset of E × E, matching the standard set-theoretic / relational-algebra sense of the word. causalatee uses "relation" this way to name a type of connection: the causal relation, the countercausal relation (see causalatee.data.constants.Relation).

Relationship

A relationship is one element of a relation -- a single ordered pair (x, y) that belongs to it, not the relation itself. "x causes y" expresses a causal relationship between x and y: i.e., (x, y) is an element of the causal relation.

This distinction is deliberate throughout causalatee's API: Relation (the enum) names relation types, while a relationship field on a per-pair record -- IdentifiedRelation.relationship -- names one pair's classification into one of those types. Read "the causal relation between smoking and cancer" as the general, type-level claim, and "there is a causal relationship between this smoking event and this cancer diagnosis" as one concrete instance of it.

Entity

One element of E -- an entity, event, or concept that can participate as the cause or the effect side of a relationship. Entities are the spans marked in a source text (e.g. via insert_entity_markers) that a relationship's first/second (or e1/e2) fields reference by id.