Syntax and Consequence Relations -- A Categorical Perspective (original) (raw)

On the proof-theoretic side, logic, roughly speaking, is mainly about the grammar of the language (syntax), and reasoning on this language (consequence relations). On the model-theoretic side, we further provides mathematical structures that evaluates the language (semantic models). Among these, syntax is perhaps the easiest part. What one usually does to specify the syntax is to first fix a set of variablesX , which almost always is chosen to be a countably infinite set, and then define the set of well-formed formulas Fml with variables being in X . Here in this paper we will confine ourselves to only consider language of algebraic nature. ‘is means that our signature for the language would be algebraic, and the only formula-forming rules would be application of function symbols. Syntax in richer context with variable bindings could become much less trivial. ‘e more interesting part of logic in our se‹ing is how to reason with the given language, and how we provide the semantics. F...

Categorical Syntax and Consequence Relations

2021

In this paper, we use a categorical and functorial set up to model the syntax and inference of logics of algebraic signature, extending previous works on algebraisation of logics. The main feature of this work is that structurality, or invariance under substitution of variables, are modelled by functoriality in this paper, resulting in a much clearer framework for algebraisation. It also provides a very nice conceptual understanding of various existing results already established in the literatures, and derives several new results as well.

First order languages: Further syntax and semantics

2011

Third of a series of articles laying down the bases for classical first order model theory. Interpretation of a language in a universe set. Evaluation of a term in a universe. Truth evaluation of an atomic formula. Reassigning the value of a symbol in a given interpretation. Syntax and semantics of a non atomic formula are then defined concurrently (this point is explained in [16], 4.2. 1). As a consequence, the evaluation of any wff string and the relation of logical implication are introduced. Depth of a formula.

Towards a Relational Treating of Language and Logical Systems

2020

Generally speaking, there are two categories of semantics theory: model-theoretic approach and proof-theoretic approach. In the first part of this paper, I will briefly analyze some inadequacies related to these two approaches, and promote an alternative relational approach, which bases semantic notions on relations between expressions. A brief discussion in general for this alternative will be provided. In the second part, I will provide a solid mathematical framework to the study of logical meanings, and show its connection with the other two approaches.

Categorical Semantics of Linear Logic

Proof theory is the result of a short and tumultuous history, developed on the periphery of mainstream mathematics. Hence, its language is often idiosyn- cratic: sequent calculus, cut-elimination, subformula property, etc. This survey is designed to guide the novice reader and the itinerant mathematician along a smooth and consistent path, investigating the symbolic mechanisms of cut- elimination, and their algebraic transcription as coherence diagrams in cate- gories with structure. This spiritual journey at the meeting point of linguistic and algebra is demanding at times, but also pleasantly rewarding: to date, no language (either formal or informal) has been studied by mathematicians as thoroughly as the language of proofs. We start the survey by a short introduction to proof theory (Chapter 1) followed by an informal explanation of the principles of denotational semantics (Chapter 2) which we express as a representation theory for proofs - generat- ing algebraic invariants modu...

An Infinitary Model of Linear Logic

Lecture Notes in Computer Science, 2015

In this paper, we construct an infinitary variant of the relational model of linear logic, where the exponential modality is interpreted as the set of finite or countable multisets. We explain how to interpret in this model the fixpoint operator Y as a Conway operator alternatively defined in an inductive or a coinductive way. We then extend the relational semantics with a notion of color or priority in the sense of parity games. This extension enables us to define a new fixpoint operator Y combining both inductive and coinductive policies. We conclude the paper by mentionning a connection between the resulting model of λ-calculus with recursion and higher-order model-checking.

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