Triseries

Triseries is a term that appears in several disciplines to denote a grouping or sequence that involves three related series, components, or dimensions. It is not a standardized technical term with a single fixed definition, and its meaning tends to vary by field and context.

In mathematics, what experts more commonly call a trivariate or triple series may be described informally as a triseries. This typically refers to a multivariate or triple sum, such as a three-variable power series. The conventional terminology uses terms like multivariate series, triple series, or trivariate power series, with coefficients indexed by three nonnegative integers and variables raised to corresponding powers. In formal work, precision usually favors specific descriptors rather than the generic label triseries.

In statistics and time-series analysis, the closest standard notion is a trivariate or multivariate time series—three related series analyzed jointly, often with vector autoregression or other multivariate models. The label triseries is not common in technical literature, but it may appear in informal writing to signify three interdependent series studied together.

In media and storytelling, triseries can describe a three-part narrative, such as a trilogy of novels or a tri-part TV series. Here the term is used descriptively rather than as a formal genre classification, and it may be interchangeable with trilogy or three-part series in everyday usage.

See also: trilogy, multivariate, triple series, trivariate.