The expressive truth functions of two-valued logic have all been identified. This paper begins the task of identifying the expressive truth functions of n-valued logic by characterizing the unary ones. These functions have distinctive algebraic, semantic, and closure-theoretic properties.
"The Expressive Unary Truth Functions of n-valued Logic." Notre Dame J. Formal Logic 46 (1) 93 - 105, 2005. https://doi.org/10.1305/ndjfl/1107220676