**The number of arguments to a function.** "Arity" is the number of arguments to a function, as used in the realm of mathematics and software engineering. Arity is useful for determining the complexity of a function. A reduction in arity with minimal impact is the goal of [[Pareto Analysis]]. # Examples - f(x,y,z) has an arity of "3". - "Distance travelled" of a flying object is primarily a function of velocity, azimuth, and drag. This is also an arity of 3. Arity is not the same term as "[[Cardinality]]", although they are very similar. # [[Entity-Relationship Diagrams]] Arity When it comes to [[Entity Relationship Categories]], "Arity" means how many different [[Entity Definition|entities]] are _involved_ in a relationship. The most common are Unary, Binary, and Trinary: - Unary - relation to self. Family tree. `Human` relates to `Human`. - Binary - most common type, direct relation between two types of entities. `Human` takes `class`. - Trinary - where a 3rd entity is required. `Human` takes `class` in `semester` **** ## Source ## Related - [[Pareto Principle]] - [[Cardinality]]