3,405 research outputs found
Constructions of free commutative integro-differential algebras
In this survey, we outline two recent constructions of free commutative
integro-differential algebras. They are based on the construction of free
commutative Rota-Baxter algebras by mixable shuffles. The first is by
evaluations. The second is by the method of Gr\"obner-Shirshov bases.Comment: arXiv admin note: substantial text overlap with arXiv:1302.004
Polynomial Interpretations over the Natural, Rational and Real Numbers Revisited
Polynomial interpretations are a useful technique for proving termination of
term rewrite systems. They come in various flavors: polynomial interpretations
with real, rational and integer coefficients. As to their relationship with
respect to termination proving power, Lucas managed to prove in 2006 that there
are rewrite systems that can be shown polynomially terminating by polynomial
interpretations with real (algebraic) coefficients, but cannot be shown
polynomially terminating using polynomials with rational coefficients only. He
also proved the corresponding statement regarding the use of rational
coefficients versus integer coefficients. In this article we extend these
results, thereby giving the full picture of the relationship between the
aforementioned variants of polynomial interpretations. In particular, we show
that polynomial interpretations with real or rational coefficients do not
subsume polynomial interpretations with integer coefficients. Our results hold
also for incremental termination proofs with polynomial interpretations.Comment: 28 pages; special issue of RTA 201
Tensors, !-graphs, and non-commutative quantum structures
Categorical quantum mechanics (CQM) and the theory of quantum groups rely
heavily on the use of structures that have both an algebraic and co-algebraic
component, making them well-suited for manipulation using diagrammatic
techniques. Diagrams allow us to easily form complex compositions of
(co)algebraic structures, and prove their equality via graph rewriting. One of
the biggest challenges in going beyond simple rewriting-based proofs is
designing a graphical language that is expressive enough to prove interesting
properties (e.g. normal form results) about not just single diagrams, but
entire families of diagrams. One candidate is the language of !-graphs, which
consist of graphs with certain subgraphs marked with boxes (called !-boxes)
that can be repeated any number of times. New !-graph equations can then be
proved using a powerful technique called !-box induction. However, previously
this technique only applied to commutative (or cocommutative) algebraic
structures, severely limiting its applications in some parts of CQM and
(especially) quantum groups. In this paper, we fix this shortcoming by offering
a new semantics for non-commutative !-graphs using an enriched version of
Penrose's abstract tensor notation.Comment: In Proceedings QPL 2014, arXiv:1412.810
Automated verification of termination certificates
In order to increase user confidence, many automated theorem provers provide
certificates that can be independently verified. In this paper, we report on
our progress in developing a standalone tool for checking the correctness of
certificates for the termination of term rewrite systems, and formally proving
its correctness in the proof assistant Coq. To this end, we use the extraction
mechanism of Coq and the library on rewriting theory and termination called
CoLoR
Formalizing real analysis for polynomials
When reasoning formally with polynomials over real numbers, or more generally real closed fields, we need to be able to manipulate easily statements featuring an order relation, either in their conditions or in their conclusion. For instance, we need to state the intermediate value theorem and the mean value theorem and we need tools to ease both their proof and their further use. For that purpose we propose a Coq library for ordered integral domains and ordered fields with decidable comparison. In this paper we present the design choices of this libraries, and show how it has been used as a basis for developing a fare amount of basic real algebraic geometry
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