148 research outputs found
Code Generation for Higher Inductive Types
Higher inductive types are inductive types that include nontrivial
higher-dimensional structure, represented as identifications that are not
reflexivity. While work proceeds on type theories with a computational
interpretation of univalence and higher inductive types, it is convenient to
encode these structures in more traditional type theories with mature
implementations. However, these encodings involve a great deal of error-prone
additional syntax. We present a library that uses Agda's metaprogramming
facilities to automate this process, allowing higher inductive types to be
specified with minimal additional syntax.Comment: 16 pages, Accepted for presentation in WFLP 201
Quotient inductive-inductive types
Higher inductive types (HITs) in Homotopy Type Theory (HoTT) allow the definition of datatypes which have constructors for equalities over the defined type. HITs generalise quotient types and allow to define types which are not sets in the sense of HoTT (i.e. do not satisfy uniqueness of equality proofs) such as spheres, suspensions and the torus. However, there are also interesting uses of HITs to define sets, such as the Cauchy reals, the partiality monad, and the internal, total syntax of type theory. In each of these examples we define several types that depend on each other mutually, i.e. they are inductive-inductive definitions. We call those HITs quotient inductive-inductive types (QIITs).
Although there has been recent progress on the general theory of HITs, there isn't yet a theoretical foundation of the combination of equality constructors and induction-induction, despite having many interesting applications. In the present paper we present a first step towards a semantic definition of QIITs. In particular, we give an initial-algebra semantics and show that this is equivalent to the section induction principle, which justifies the intuitively expected elimination rules
Three equivalent ordinal notation systems in cubical Agda
We present three ordinal notation systems representing ordinals below epsilon zero in type theory, using recent type-theoretical innovations such as mutual inductive-inductive definitions and higher inductive types. We show how ordinal arithmetic can be developed for these systems, and how they admit a transfinite induction principle. We prove that all three notation systems are equivalent, so that we can transport results between them using the univalence principle. All our constructions have been implemented in cubical Agda
Response to “Comment on ‘Effective thermal conductivity in thermoelectric materials’” [J. Appl. Phys. 113
Bindings as bounded natural functors
We present a general framework for specifying and reasoning about syntax with bindings. Abstract binder types are modeled using a universe of functors on sets, subject to a number of operations that can be used to construct complex binding patterns and binding-aware datatypes, including non-well-founded and infinitely branching types, in a modular fashion. Despite not committing to any syntactic format, the framework is “concrete” enough to provide definitions of the fundamental operators on terms (free variables, alpha-equivalence, and capture-avoiding substitution) and reasoning and definition principles. This work is compatible with classical higher-order logic and has been formalized in the proof assistant Isabelle/HOL
Trends in drug use among students in Brazil: analysis of four surveys in 1987, 1989, 1993 and 1997
Vorbereitung von Flugversuchen zur Kennwertermittlung des Nurflügel-Segelflugzeuges SB 13
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