24 research outputs found
Foundations of Software Science and Computation Structures
This open access book constitutes the proceedings of the 25th International Conference on Foundations of Software Science and Computational Structures, FOSSACS 2022, which was held during April 4-6, 2022, in Munich, Germany, as part of the European Joint Conferences on Theory and Practice of Software, ETAPS 2022. The 23 regular papers presented in this volume were carefully reviewed and selected from 77 submissions. They deal with research on theories and methods to support the analysis, integration, synthesis, transformation, and verification of programs and software systems
Continuous Functions on Final Comodels of Free Algebraic Theories
In 2009, Ghani, Hancock and Pattinson gave a tree-like representation of stream processors A[N] → B[N]. In 2021, Garner showed that this representation can be established in terms of algebraic theory and comodels: the set of infinite streams A[N] is the final comodel of the algebraic theory of A-valued input [T][A] and the set of stream processors Top(A[N] , B[N]) can be seen as the final [T][A]-[T][B]-bimodel. In this paper, we generalize Garner's results to the case of free algebraic theories
Stream processors and comodels
In 2009, Hancock, Pattinson and Ghani gave a coalgebraic characterisation of
stream processors drawing on ideas of
Brouwerian constructivism. Their stream processors have an intensional
character; in this paper, we give a corresponding coalgebraic characterisation
of extensional stream processors, i.e., the set of continuous functions
. Our account sites both our result and that of
op. cit. within the apparatus of comodels for algebraic effects originating
with Power-Shkaravska. Within this apparatus, the distinction between
intensional and extensional equivalence for stream processors arises in the
same way as the the distinction between bisimulation and trace equivalence for
labelled transition systems and probabilistic generative systems.Comment: 24 pages; v4: final accepted versio
Continuous Functions on Final Comodels of Free Algebraic Theories
In 2009, Ghani, Hancock and Pattinson gave a tree-like representation of
stream processors . In 2021, Garner
showed that this representation can be established in terms of algebraic theory
and comodels: the set of infinite streams is the final comodel
of the algebraic theory of -valued input and the set of
stream processors can be seen as
the final --bimodel. In this paper, we generalize
Garner's results to the case of free algebraic theories.Comment: 17 page
Programming Languages and Systems
This open access book constitutes the proceedings of the 29th European Symposium on Programming, ESOP 2020, which was planned to take place in Dublin, Ireland, in April 2020, as Part of the European Joint Conferences on Theory and Practice of Software, ETAPS 2020. The actual ETAPS 2020 meeting was postponed due to the Corona pandemic. The papers deal with fundamental issues in the specification, design, analysis, and implementation of programming languages and systems
Stream Processors and Comodels
In 2009, Ghani, Hancock and Pattinson gave a coalgebraic characterisation of stream processors A^? ? B^? drawing on ideas of Brouwerian constructivism. Their stream processors have an intensional character; in this paper, we give a corresponding coalgebraic characterisation of extensional stream processors, i.e., the set of continuous functions A^? ? B^?. Our account sites both our result and that of op. cit. within the apparatus of comodels for algebraic effects originating with Power-Shkaravska
Towards a Uniform Theory of Effectful State Machines
Using recent developments in coalgebraic and monad-based semantics, we
present a uniform study of various notions of machines, e.g. finite state
machines, multi-stack machines, Turing machines, valence automata, and weighted
automata. They are instances of Jacobs' notion of a T-automaton, where T is a
monad. We show that the generic language semantics for T-automata correctly
instantiates the usual language semantics for a number of known classes of
machines/languages, including regular, context-free, recursively-enumerable and
various subclasses of context free languages (e.g. deterministic and real-time
ones). Moreover, our approach provides new generic techniques for studying the
expressivity power of various machine-based models.Comment: final version accepted by TOC
Runners in action
Runners of algebraic effects, also known as comodels, provide a mathematical
model of resource management. We show that they also give rise to a programming
concept that models top-level external resources, as well as allows programmers
to modularly define their own intermediate "virtual machines". We capture the
core ideas of programming with runners in an equational calculus
, which we equip with a sound and coherent
denotational semantics that guarantees the linear use of resources and
execution of finalisation code. We accompany with
examples of runners in action, provide a prototype language implementation in
OCaml, as well as a Haskell library based on .Comment: ESOP 2020 final version + online appendi