Formal and Foundational Research: Categorical, Type-Theoretic, and Logical Developments

Report on Current Developments in the Research Area

General Direction of the Field

The recent developments in the research area indicate a significant shift towards more foundational and formal approaches, particularly in the context of categorical and type-theoretic frameworks. There is a growing emphasis on extending and refining existing theories to accommodate more complex and general scenarios, often leveraging novel concepts and tools from category theory, type theory, and automata theory.

One of the key trends is the exploration of causality and event structures within various computational models, such as hypergraph rewriting and λ-calculus. This direction seeks to establish a more rigorous understanding of the causal relationships between events in these models, potentially leading to new algorithms and methodologies for analyzing and predicting computational behaviors.

Another notable trend is the formalization and generalization of logical fragments and their properties. Researchers are focusing on defining new logical fragments that extend or restrict existing ones, with the aim of understanding their computational complexity and expressive power. This work often involves proving decidability and complexity results for these fragments, which can have significant implications for both theoretical and practical applications.

The field is also witnessing advancements in the study of domain theory and the properties of directed complete partial orders (dcpos). Recent work has addressed the faithfulness of categories of dcpos, leading to refinements and extensions of known results. This includes the identification of new classes of dcpos that exhibit desirable properties, such as being dominated or well-filtered, and the exploration of their implications for the broader domain theory.

In the realm of type theory and formalization, there is a move towards intensional type theories and the use of advanced type systems like Cubical Agda. These efforts aim to formalize and generalize results that were previously confined to extensional settings, demonstrating the potential of intensional type theories for handling inductive and coinductive data types more effectively.

Noteworthy Papers

  • Hypergraph rewriting and Causal structure of λ-calculus: Introduces a novel approach to defining causality in graph rewriting and extends it to λ-calculus, potentially paving the way for new algorithms in event analysis.

  • The Adjacent Fragment and Quine's Limits of Decision: Defines a new logical fragment with interesting complexity properties, contributing to the understanding of logical fragments and their computational limits.

  • The category of well-filtered dcpos is not Γ-faithful: Refines the understanding of dcpos categories, identifying new classes of dcpos and their properties, which could have significant implications for domain theory.

  • Formalising inductive and coinductive containers: Demonstrates the formalization of container theory in intensional type theory, showcasing the potential of Cubical Agda for coinductive proofs and generalizing previous results.

Sources

Hypergraph rewriting and Causal structure of $λ-$calculus

The Adjacent Fragment and Quine's Limits of Decision

The category of well-filtered dcpos is not $Γ$-faithful

Formalising inductive and coinductive containers

Two or three things I know about tree transducers

Normal forms in Virus Machines