Nominal type systems with variance, a core of subtype relation in object-oriented programming languages like Java, C# and Scala, have been extensively studied by Kennedy and Pierce; they have shown the undecidability of the subtyping between ground types and proposed the decidable fragments of such type systems. However, precise intraprocedural analysis of object-oriented code may require a reasoning about the relations of open types. In this paper, we formalize and investigate the satisfiability problem for nominal subtyping with variance. We define the problem in the context of first-order logic. We show that, although the non-expansive ground nominal subtyping with variance is decidable, its satisfiability problem is undecidable. Our proof uses a remarkably small fragment of the type system. In fact, we demonstrate that even for the non-expansive class tables with only nullary and unary covariant and invariant type constructors, the satisfiability of quantifier-free conjunctions of positive subtyping atoms is undecidable.
Wed 17 JulDisplayed time zone: Belfast change
13:30 - 15:10 | |||
13:30 20mResearch paper | Transient Typechecks are (Almost) Free Research Papers Richard Roberts Victoria University of Wellington, Stefan Marr University of Kent, Michael Homer Victoria University of Wellington, James Noble Victoria University of Wellington DOI Media Attached | ||
13:50 20mResearch paper | A Typing Discipline for Hardware Interfaces Research Papers DOI Media Attached | ||
14:10 20mResearch paper | Minimal Session Types Research Papers Alen Arslanagić University of Groningen, Jorge A. Pérez University of Groningen, The Netherlands, Erik Voogd University of Oslo DOI Media Attached | ||
14:30 20mResearch paper | Julia's Efficient Algorithm for Subtyping Unions and Covariant Tuples Research Papers Benjamin Chung Northeastern University, Francesco Zappa Nardelli Inria, Jan Vitek Northeastern University DOI Media Attached | ||
14:50 20mResearch paper | On Satisfiability of Nominal Subtyping with Variance Research Papers Aleksandr Misonizhnik Saint-Petersburg State University, Dmitry Mordvinov Saint-Petersburg State University, JetBrains Research DOI Media Attached |