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Invited talk
Workshop papers
11:00  A positive perspective on term representation: work in progress PRESENTER: JuiHsuan Wu ABSTRACT. We use the focused proof system LJF as a framework for describing term structures and substitution. Since the proof theory of LJF does not pick a canonical polarization for primitive types, two different approaches to term representation arise. When primitive types are given the negative bias, LJF proofs encode term structures as treelike structures in a familiar fashion. In this situation, cut elimination also yields the familiar notion of substitution. On the other hand, when primitive types are given the positive bias, LJF proofs yield a structure in which explicit sharing of term structures is possible. In this situation, cut elimination yields a different notion of substitution. We illustrate these two approaches to term representation by applying them to the encoding of untyped λterms. More details can be found at http://www.lix.polytechnique.fr/Labo/Dale.Miller/papers/lfmtp22positiveperspective.pdf. 
11:45  An Implementation of Set Theory with Pointed Graphs in Dedukti PRESENTER: Thomas Traversié ABSTRACT. Dedukti is a typechecker for the lambdapi calculus modulo theory, a logical framework that allows the extension of conversion with userdefined rewrite rules. In this paper, we present the implementation of a version of DowekMiquel’s intuitionistic set theory in Dedukti. To do so, we adapt this theory  based on the concept of pointed graphs  from Deduction modulo theory to lambdapi calculus modulo theory, and we formally write the proofs in Dedukti. In particular, this implementation requires the definition of a deep embedding of a certain class of formulas, as well as its interpretation in the theory. More details can be found at https://hal.archivesouvertes.fr/hal03740004. 
Lunches will be held in Taub hall and in The Grand Water Research Institute.
Frank Pfenning special session: invited talk
Frank Pfenning special session: contributed talks
15:00  Associativity or NonAssociativity, Local or Global! PRESENTER: Eben Blaisdell ABSTRACT. Lambek's two calculi, the associative one and the nonassociative one, have their advantages and disadvantages for the analysis of natural language syntax by means of categorial grammar. In some cases, associativity leads to overgeneration, i.e., validation of grammatically incorrect sentences. In other situations, associativity is useful. We will discuss two approaches. One approach, developed by Morrill and Moortgat, begins with the associative calculus and reconstructs local nonassociativity by means of the socalled bracket modalities, ultimately leading to Morrill's CatLog parser. Bracket modalities interact in a subtle way with the subexponential modalities originating in linear logic. Another approach, developed by Moot and Retoré, begins with the nonassociative calculus and utilizes multimodalities, ultimately leading to the Grail parser. We enhance the latter approach in our IJCAR 2022 paper, showing that local associativity may be expressed by means of subexponentials. Some aspects of the two approaches touch Frank Pfenning's work on ordered logic and on adjoint logic. We discuss decidability and undecidability results in both approaches. 
Frank Pfenning special session: invited talk
Frank Pfenning special session: contributed talks
17:00  A (Logical) Framework for Collaboration ABSTRACT. A common interest in logical frameworks formed the basis for many years of fruitful and enjoyable collaboration with Frank and his students, both directly and indirectly. Frank’s development of the Twelf system was instrumental in enabling the use of LF for specifying a wide range of formalisms, ranging from “pure logics” to “practical programming languages.” Most importantly, the Twelf totality checker for proving AllExists statements allowed for a humanreadable and easily developed proof of type safety for the Standard ML language that not only verified what we already knew, but also fostered the development of a new language definition methodology wellsuited to the demands of working at scale. 
17:15  Type refinement as a unifying principle ABSTRACT. I will discuss some personal perspectives on the "Type Refinement" project initiated by Frank several decades ago, and how it has influenced my research over the years since my PhD.

17:30  Language Minimalism and Logical Frameworks PRESENTER: Chris Martens ABSTRACT. In the design of tools, languages, and frameworks, Frank has been a consistent advocate for a particular flavor of aesthetic minimalism. A valuable trait of minimalist frameworks and tiny programming languages is that they facilitate implementation and reimplementation in multiple contexts with various interfaces. This principle has guided our (Chris and Rob’s) work at and beyond Carnegie Mellon, including for some recent projects we've pursued together. We'll talk about some of our Frankadjacent projects we've reimplemented on the web, how language minimalism contributed to their success, lessons learned, and a path forward for extending the reach and application of logical frameworks.

17:45  Logics for Robotics 