In mathematical logic, various sublanguages of set theory are decidable.Cantone, D., E. G. Omodeo and A. Policriti, "Set Theory for Computing. From Decision Procedures to Logic Programming with Sets," Monographs in Computer Science, Springer, 2001."Decision procedures for elementary sublanguages of set theory: XIII. Model graphs, reflection and decidability", by Franco Parlamento and Alberto Policriti Journal of Automated Reasoning, Volume 7, Issue 2 (June 1991), Pages: 271 - 284 They are referred to as syllogistics. Together with the operations of set algebra, decidable languages include: Sets with monotone, additive, and multiplicative functions, but without quantifiers."A Decision Procedure for a Sublanguage of Set Theory Involving Monotone, Additive, and Multiplicative Functions", by Domenico Cantone and et al. Sets with restricted quantifiers."A tableau-based decision procedure for a fragment of set theory involving a restricted form of quantification", by Domenico Cantone, Calogero G. Zarba, Viale A. Doria, 1997
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