438 research outputs found
Translating Combinatory Reduction Systems into the Rewriting Calculus
Long version. Colloque avec actes et comité de lecture. internationale.International audienceThe last few years have seen the development of the rewriting calculus (or rho-calculus, RHO) that extends first order term rewriting and lambda-calculus. The integration of these two latter formalisms has been already handled either by enriching first-order rewriting with higher-order capabilities, like in the Combinatory Reduction Systems, or by adding to lambda-calculus algebraic features. The different higher-order rewriting systems and the rewriting calculus share similar concepts and have similar applications, and thus, it seems natural to compare these formalisms. We analyze in this paper the relationship between the Rewriting Calculus and the Combinatory Reduction Systems and we present a translation of CRS-terms and rewrite rules into rho-terms and we show that for any CRS-reduction we have a corresponding rho-reduction
From nominal to higher-order rewriting and back again
We present a translation function from nominal rewriting systems (NRSs) to
combinatory reduction systems (CRSs), transforming closed nominal rules and
ground nominal terms to CRSs rules and terms, respectively, while preserving
the rewriting relation. We also provide a reduction-preserving translation in
the other direction, from CRSs to NRSs, improving over a previously defined
translation. These tools, together with existing translations between CRSs and
other higher-order rewriting formalisms, open up the path for a transfer of
results between higher-order and nominal rewriting. In particular, techniques
and properties of the rewriting relation, such as termination, can be exported
from one formalism to the other.Comment: 41 pages, journa
Weak orthogonality implies confluence : the higher-order case
In this paper we prove confluence for weakly orthogonal Higher-Order Rewriting Systems. This generalises all the known `confluence by orthogonality' results
Definitions by Rewriting in the Calculus of Constructions
The main novelty of this paper is to consider an extension of the Calculus of
Constructions where predicates can be defined with a general form of rewrite
rules. We prove the strong normalization of the reduction relation generated by
the beta-rule and the user-defined rules under some general syntactic
conditions including confluence. As examples, we show that two important
systems satisfy these conditions: a sub-system of the Calculus of Inductive
Constructions which is the basis of the proof assistant Coq, and the Natural
Deduction Modulo a large class of equational theories.Comment: Best student paper (Kleene Award
CRSX - Combinatory Reduction Systems with Extensions
Combinatory Reduction Systems with Extensions (CRSX) is a system
available from http://crsx.sourceforge.net and characterized by
the following properties:
- Higher-order rewriting engine based on pure Combinatory Reduction Systems with full strong reduction (but no specified reduction strategy).
- Rule and term syntax based on lambda-calculus and term rewriting conventions including Unicode support.
- Strict checking and declaration requirements to avoid idiosyncratic errors in rewrite rules.
- Interpreter is implemented in Java 5 and usable stand-alone as well as from an Eclipse plugin (under development).
- Includes a custom parser generator (front-end to JavaCC parser generator) designed to ease parsing directly into higher-order abstract syntax (as well as permitting the use of custom syntax in rules files).
- Experimental (and evolving) sort system to help rule management.
- Compiler from (well-sorted deterministic subset of) CRSX to stand-alone C code
Computation in director string calculus
In this thesis we introduce a modified version of Director String Calculus (MDSC) which preserves the applicative structure of the original lambda terms and captures the strong reduction as opposed to weak reduction of the original Director String Calculus (DSC). Furthermore, our reduction system provides an environment which supports the nonatomic nature of substitution operation and hence can lend itself to parallel and optimal reduction. We shall compare our reduction method with other reduction methods, and discuss some of the advantages and disadvantages of our method
On Constructor Rewrite Systems and the Lambda Calculus
We prove that orthogonal constructor term rewrite systems and lambda-calculus
with weak (i.e., no reduction is allowed under the scope of a
lambda-abstraction) call-by-value reduction can simulate each other with a
linear overhead. In particular, weak call-by- value beta-reduction can be
simulated by an orthogonal constructor term rewrite system in the same number
of reduction steps. Conversely, each reduction in a term rewrite system can be
simulated by a constant number of beta-reduction steps. This is relevant to
implicit computational complexity, because the number of beta steps to normal
form is polynomially related to the actual cost (that is, as performed on a
Turing machine) of normalization, under weak call-by-value reduction.
Orthogonal constructor term rewrite systems and lambda-calculus are thus both
polynomially related to Turing machines, taking as notion of cost their natural
parameters.Comment: 27 pages. arXiv admin note: substantial text overlap with
arXiv:0904.412
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