379 research outputs found
Intuitionistic fixed point theories over Heyting arithmetic
In this paper we show that an intuitionistic theory for fixed points is
conservative over the Heyting arithmetic with respect to a certain class of
formulas. This extends partly the result of mine. The proof is inspired by the
quick cut-elimination due to G. Mints
Efficient Data Structures for Automated Theorem Proving in Expressive Higher-Order Logics
Church's Simple Theory of Types (STT), also referred to as classical higher-order logik, is an elegant and expressive formal system built on top of the simply typed λ-calculus. Its mechanisms of explicit binding and quantification over arbitrary sets and functions allow the representation of complex mathematical concepts and formulae in a concise and unambiguous manner. Higher-order automated theorem proving (ATP) has recently made major progress and several sophisticated ATP systems for higher-order logic have been developed, including Satallax, Osabelle/HOL and LEO-II. Still, higher-order theorem proving is not as mature as its first-order counterpart, and robust implementation techniques for efficient data structures are scarce.
In this thesis, a higher-order term representation based upon the polymorphically typed λ-calculus is presented. This term representation employs spine notation, explicit substitutions and perfect term sharing for efficient term traversal, fast β-normalization and reuse of already constructed terms, respectively. An evaluation of the term representation is performed on the basis of a heterogeneous benchmark set. It shows that while the presented term data structure performs quite well in general, the normalization results indicate that a context dependent choice of reduction strategies is beneficial.
A term indexing data structure for fast term retrieval based on various low-level criteria is presented and discussed. It supports symbol-based term retrieval, indexing of terms via structural properties, and subterm indexing
Normalisation Control in Deep Inference via Atomic Flows
We introduce `atomic flows': they are graphs obtained from derivations by
tracing atom occurrences and forgetting the logical structure. We study simple
manipulations of atomic flows that correspond to complex reductions on
derivations. This allows us to prove, for propositional logic, a new and very
general normalisation theorem, which contains cut elimination as a special
case. We operate in deep inference, which is more general than other syntactic
paradigms, and where normalisation is more difficult to control. We argue that
atomic flows are a significant technical advance for normalisation theory,
because 1) the technique they support is largely independent of syntax; 2)
indeed, it is largely independent of logical inference rules; 3) they
constitute a powerful geometric formalism, which is more intuitive than syntax
Efficiently Simulating Higher-Order Arithmetic by a First-Order Theory Modulo
In deduction modulo, a theory is not represented by a set of axioms but by a
congruence on propositions modulo which the inference rules of standard
deductive systems---such as for instance natural deduction---are applied.
Therefore, the reasoning that is intrinsic of the theory does not appear in the
length of proofs. In general, the congruence is defined through a rewrite
system over terms and propositions. We define a rigorous framework to study
proof lengths in deduction modulo, where the congruence must be computed in
polynomial time. We show that even very simple rewrite systems lead to
arbitrary proof-length speed-ups in deduction modulo, compared to using axioms.
As higher-order logic can be encoded as a first-order theory in deduction
modulo, we also study how to reinterpret, thanks to deduction modulo, the
speed-ups between higher-order and first-order arithmetics that were stated by
G\"odel. We define a first-order rewrite system with a congruence decidable in
polynomial time such that proofs of higher-order arithmetic can be linearly
translated into first-order arithmetic modulo that system. We also present the
whole higher-order arithmetic as a first-order system without resorting to any
axiom, where proofs have the same length as in the axiomatic presentation
Quantum bayesian decision‑making
As a compact representation of joint probability distributions over a dependence graph of
random variables, and a tool for modelling and reasoning in the presence of uncertainty,
Bayesian networks are of great importance for artificial intelligence to combine domain
knowledge, capture causal relationships, or learn from incomplete datasets. Known as a
NP-hard problem in a classical setting, Bayesian inference pops up as a class of algorithms worth to explore in a quantum framework. This paper explores such a research direction and improves on previous proposals by a judicious use of the utility function in an entangled configuration. It proposes a completely quantum mechanical decision-making process with a proven computational advantage. A prototype implementation in Qiskit (a Python based program development kit for the IBM Q machine) is discussed as a proof-of-concept.This work is fnanced by the ERDF–European Regional Development Fund through the Operational Programme for Competitiveness and Internationalisation–COMPETE 2020 Programme and by National Funds through the Portuguese funding agency, FCT, within project POCI-01- 0145-FEDER-030947. The frst author was further supported by project NORTE-01-0145- FEDER-000037, funded by Norte Portugal Regional Operational Programme (NORTE 2020), under the PORTUGAL 2020 Partnership Agreement
On the Introduction of Guarded Lists in Bach: Expressiveness, Correctness, and Efficiency Issues
Concurrency theory has received considerable attention, but mostly in the
scope of synchronous process algebras such as CCS, CSP, and ACP. As another way
of handling concurrency, data-based coordination languages aim to provide a
clear separation between interaction and computation by synchronizing processes
asynchronously by means of information being available or not on a shared
space. Although these languages enjoy interesting properties, verifying program
correctness remains challenging. Some works, such as Anemone, have introduced
facilities, including animations and model checking of temporal logic formulae,
to better grasp system modelling. However, model checking is known to raise
performance issues due to the state space explosion problem. In this paper, we
propose a guarded list construct as a solution to address this problem. We
establish that the guarded list construct increases performance while strictly
enriching the expressiveness of data-based coordination languages. Furthermore,
we introduce a notion of refinement to introduce the guarded list construct in
a correctness-preserving manner.Comment: In Proceedings ICE 2023, arXiv:2308.0892
- …