
F.J. de Vries.
On Undefined and Meaningless in Lambda Definability
in proceedings of 1st International Conference on Formal Structures for Computation and Deduction (FSCD 2016)
pdf, DOI:
10.4230/LIPIcs.FSCD.2016.18, URL: http://drops.dagstuhl.de/opus/volltexte/2016/5978/
AbstractWe distinguish between undefined terms as used in lambda definability of partial recursive functions and meaningless terms as used in infinite lambda calculus for the infinitary terms models that generalise the Bohm model. While there are uncountable many known sets of meaningless terms, there are four known sets of undefined terms. Two of these four are sets of meaningless terms. In this paper we first present set of sufficient conditions for a set of lambda terms to serve as set of undefined terms in lambda definability of partial functions. The four known sets of undefined terms satisfy these conditions. Next we locate the smallest set of meaningless terms satisfying these conditions. This set sits very low in the lattice of all sets of meaningless terms. Any larger set of meaningless terms than this smallest set is a set of undefined terms. Thus we find uncountably many new sets of undefined terms. As an unexpected bonus of our careful analysis of lambda definability we obtain a natural modification, strict lambdadefinability, which allows for a Barendregt style of proof in which the representation of composition is truly the composition of representations.

A. Kurz, A. Pardo, D. Petrisan, P. Severi and F.J. de Vries.
Approximation of Nested Fixpoints – A Coalgebraic View of Parametric Dataypes
in proceedings of 6th Conference on Algebra and Coalgebra in Computer Science (CALCO 2015)
pdf,
DOI: 10.4230/LIPIcs.CALCO.2015.205, URL: http://drops.dagstuhl.de/opus/volltexte/2015/5535/
Abstract The question addressed in this paper is how to correctly approximate infinite data given by
systems of simultaneous corecursive definitions. We devise a categorical framework for reasoning
about regular datatypes, that is, datatypes closed under products, coproducts and fixpoints.
We argue that the right methodology is on one hand coalgebraic (to deal with possible non
termination and infinite data) and on the other hand 2categorical (to deal with parameters in
a disciplined manner). We prove a coalgebraic version of Bekič lemma that allows us to reduce
simultaneous fixpoints to a single fix point. Thus a possibly infinite object of interest is regarded
as a final coalgebra of a manysorted polynomial functor and can be seen as a limit of finite
approximants. As an application, we prove correctness of a generic function that calculates the
approximants on a large class of data types.

P. Severi and F.J. de Vries.
The Infinitary Lambda Calculus of the Infinite
Eta Bohm Trees
in Mathematical Structures in Computer Science (FirstView Article: 17 August 2015): Computing with lambdaterms:
A special issue dedicated to Corrado Böhm for his 90th birthday pdf DOI: http://dx.doi.org/10.1017/S096012951500033X
Abstract In this paper we introduce a strong form
of eta reduction called etabang that we use to construct a
confluent and normalising infinitary lambda calculus, of
which the normal forms correspond to Barendregt’s infinite
eta Bohm trees. This new infinitary perspective on the set
of infinite eta Bohm trees allows us to prove that the set
of infinite eta B ̈hm trees is a model of the lambda
calculus. The model is of interest because it has the same
local structure as Scott’s Dinfinitymodels, i.e. two
finite lambda terms are equal in the infinite eta B ̈hm
model if and only if they have the same interpretation in
Scott’s Dinfinitymodels

A. Kurz, D. Petrisan, P. Severi and F.J. de Vries.
Nominal Coalgebraic Data Types with Applications to Lambda Calculus
in LMCS 2013, volume 9(4), paper 20, pages 152, 2013.
pdf
Abstract We investigate final coalgebras in nominal sets. This allows us to define types of infinite data with binding for which all constructions automatically respect alpha equivalence. We give applications to the infinitary lambda calculus.

P. Severi and F.J. de Vries.
Completeness of Conversion between Reactive
Programs for Ultrametric Models
in Proceedings of the Typed Lambda Calculi and Applications, 11th
International Conference, TLCA 2013, Eindhoven, The Netherlands, June 2628,
2013. SLNCS volume 7941, pages 221235, 2013.
.
pdf
Abstract In 1970 Friedman proved completeness of
beta eta conversion in the simplytyped lambda calculus
for the settheoretical model. Re cently Krishnaswami and
Benton have captured the essence of Hudak’s reactive
programs in an extension of simply typed lambda calculus
with causal streams and a temporal modality and provided
this typed lambda calculus for reactive programs with a
sound ultrametric semantics. We show that beta eta
conversion in the typed lambda calculus of reac tive
programs is complete for the ultrametric model.

P. Severi and F.J. de Vries.
Pure Type Systems with Corecursion on Streams
in Proceedings of the 17th ACM SIGPLAN International Conference on Functional Programming, ICFP 2012.
pdf
Abstract In this paper, we use types for ensuring that programs involving
streams are wellbehaved. We extend pure type systems with a type
constructor for streams, a modal operator next and a fixed point
operator for expressing corecursion. This extension is called Pure
Type Systems with Corecursion (CoPTS). The typed lambda calcu
lus for reactive programs defined by Krishnaswami and Benton can
be obtained as a CoPTS. CoPTS’s allow us to study a wide range
of typed lambda calculi extended with corecursion using only one
framework. In particular, we study this extension for the calculus of
constructions which is the underlying formal language of Coq. We
use the machinery of infinitary rewriting and formalize the idea of
wellbehaved programs using the concept of infinitary normalization. We study the properties of infinitary weak and strong normalization for CoPTS’s. The set of finite and infinite terms is defined
as a metric completion. We shed new light on the meaning of the
modal operator by connecting the modality with the depth used to
define the metric. This connection is the key to the proofs of infinitary weak and strong normalization

P. Severi and F.J. de Vries.
Meaningless Sets in Infinitary Combinatory Logic
in proceedings of RTA 2012, the 23rd International Conference on Rewriting Techniques and Applications. Editor Ashish Tiwari. Nagoya, May 28 June 2, 2012. Leibniz International
Proceedings in Informatics (LIPIcs) volume 15. Pages 288304.
pdf
Abstract In this paper we study meaningless sets in infinitary combinatory logic. So far only a handful of
meaningless sets were known. We show that there are uncountably many meaningless sets. As an
application to the semantics of finite combinatory logics, we show that there exist uncountably
many combinatory algebras that are not a lambda algebra. We also study ways of weakening the
axioms of meaningless sets to get, not only sufficient, but also necessary conditions for having
confluence and normalisation.

P. Severi and F.J. de Vries.
Weakening the Axiom of Overlap in
Infinitary Lambda Calculus
in proceedings of RTA2011: the 22nd International Conference on
Rewriting Techniques and Applications. Editor Manfred SchmidtSchauß. Novi
Sad. May 30  June 1, 2011. Leibniz International
Proceedings in Informatics (LIPIcs) volume 10. Pages 313328.
pdf
Abstract In this paper we present a set of necessary and sufficient conditions on a set of lambda terms
to serve as the set of meaningless terms in an infinitary bottom extension of lambda calculus.
So far only a set of sufficient conditions was known for choosing a suitable set of meaningless
terms to make this construction produce confluent extensions. The conditions covered the three
main known examples of sets of meaningless terms. However, the much later construction of
many more examples of sets of meaningless terms satisfying the sufficient conditions renewed the
interest in the necessity question and led us to reconsider the old conditions.
The key idea in this paper is an alternative solution for solving the overlap between beta
reduction and bottom reduction. This allows us to reformulate the Axiom of Overlap, which now
determines together with the other conditions a larger class of sets of meaningless terms. We
show that the reformulated conditions are not only sufficient but also necessary for obtaining a
confluent and normalizing infinitary lambda beta bottom calculus. As an interesting consequence
of the necessity proof we obtain for infinitary lambda calculus with beta and bot reduction that
confluence implies normalization.

A. Kurz, D. Petrisan,
P. Severi and F.J. de Vries.
An AlphaCorecursion Principle
for the Infinitary Lambda Calculus
in postproceedings of CMCS 2012: the 11th International Workshop on Coalgebraic Methods in Computer Science.
31 March  1 April 2012, Tallinn, Estonia. SLNCS volume 7399, pages 130149, 2012.
pdf
Abstract Gabbay and Pitts proved that lambdaterms up to alphaequivalence constitute an initial algebra for a certain endofunctor on
the category of nominal sets. We show that the terms of the infinitary
lambdacalculus form the final coalgebra for the same functor. This allows us to give a corecursion principle for alphaequivalence classes of
finite and infinite terms. As an application, we give corecursive definitions of substitution and of infinite normal forms (Bohm, LevyLongo
and Berarducci trees).

P. Severi and F.J. de Vries.
Decomposing the Lattice of Meaningless Sets
in the Infinitary Lambda Calculus
in proceedings of WoLLIC 2011, Logic, Language, Information and Computation 
18th International Workshop, Philadelphia, PA, USA, May 1820, 2011. Editors
Lev D. Beklemishev and Ruy de Queiroz. SLNAI 6642, pages 210227, 2011.
pdf
Abstract The notion of a meaningless set has been defined for infinitary lambda calculus axiomatically. Standard examples of meaningless
sets are sets of terms that have no head normal form, the set of terms
without weak head normal form and the set of rootactive terms. The
collection of meaningless sets is a lattice. In this paper, we study the
way this lattices decompose as union of more elementary key intervals.
We also analyse the distribution of the sets of meaningless terms in the
lattice by selecting some sets as key vertices and study the cardinality in
the intervals between key vertices. As an application, we prove that the
lattice of meaningless sets is neither distributive nor modular. Interest
ingly, the example translates into a counterexample that the lattice of
lambda theories is not modular.

J.R. Kennaway, P. Severi, M.R. Sleep, and F.J. de Vries.
Infinite rewriting: from syntax to semantics,
in proceedings of Processes, Terms and Cycles: Steps on the Road to
Infinity: Essays dedicated to Jan Willem Klop on the Occasion of
His 60th Birthday, editors: A. Middeldorp, V. van Oostrom,
F. van Raamsdonk and R. de Vrijer. SLNCS 3838, pages 148172, 2005.
pdf
Part one of this paper is a brief summary of the theory of infinitary
rewriting; part two presents as application recent work presented at CSL05 and TLCA05 plus some new results by Severi and de Vries on the lattice of
tree semantics for lambda calculus. Each tree semantics consist of the set of
normal forms of a confluent and normalising infinitary extension of lambda
calculus build from a set of "meaningless" terms. Using their syntactic
descriptions these sets of meaningless terms can be ordered into a rich
lattice, providing some insight in the even richer lattice of lambda models.

P. Severi and F.J. de Vries.
Separability of infinite lambda terms
in proceedings of the LCTTNL Workshop: The
second workshop on Lambda Calculus, Type Theory and Natural
Language, King's College London, 12th September 2005. Page 112.
pdf
Abstract Infinite lambda calculi extend finite lambda
calculus with infinite terms and transfinite reduction.
In this paper we extend some classical results of finite lambda calculus
to infinite terms.
First we extend to infinite terms is
B\"ohm Theorem which states the
separability of two finite $\beta \eta$normal forms.
Next we extend to infinite terms is
the equivalence of
the prefix relation up to infinite eta expansions and
the contextual preorder that observes
head normal forms.
Finally we
prove that the theory given
by
equality of $\infty \eta$B\"ohm trees
is the
largest theory induced by
the confluent and normalising
infinitary lambda calculi extending the calculus of
B\"ohm trees.

P. Severi and F.J. de Vries.
Order Structures on Böhmlike Models
Conference paper in Luke Ong, editor, Computer Science Logic: 19th
International Workshop, CSL 2005, 14th Annual Conference of the
EACSL, Oxford, UK. August 2225, 2005.
(Lecture Notes
in Computer Science 3634), SpringerVerlag. Page 103116. 2005.
dvi, ps and pdf
Abstract In [Kennawayde Vries 2003] we presented a general construction of
tree semantics for lambda calculus parametrised by a set of
"meaningless" terms. Here we give many new examples of meaningless
sets. We study whether the resulting tree semantics are orderable. The
six principal models (including the Böhm and the LévyLongo model) are
orderable by the prefix relation. The Berarducci model is also
orderable. However, orderability is not the norm. We give a syntactic
proof that at least 2^c such tree semantics are unorderable, where c
is the cardinality of the continuum. Salibra's Theorem is a corollary.
P. Severi and F.J. de Vries.
Continuity and Discontinuity in Lambda Calculus
Conference paper in Pawel Urzyczyn, editor, Typed Lambda Calculus and
Applications, Proceedings of the 7th International Conference,
TLCA 2005,
Nara Japan, April 2123 2005. (Lecture Notes
in Computer Science 3461), SpringerVerlag. Page 369385. 2005.
dvi, ps and pdf
Abstract
In [Kennawayde Vries 2003] we presented a general construction of tree
semantics from a set of "meaningless" terms. Properties of these semantics have
not been studied before. Observing that Barendregt's Böhm model construction
for lambda calculus depends heavily on continuity, in contrast to our general
construction, and that the Berarducci model is not continuous, it is a natural
question to ask when a tree model of the lambda calculus is continuous. We
prove that the only continuous trees semantics are the Böhm and the LevyLongo
model and that only these two models have an approximation theorem and
continuous context operators.
J.R. Kennaway and F.J. de Vries.
Infinitary Rewriting.
Chapter 12 in Terese, editor, Term Rewriting
Systems (Cambridge Tracts in Theoretical Computer Science
55), Cambridge University Press. Page 668711. 2003. Erratum.
dvi, ps and pdf
Abstract
In this chapter we develop a general
theory of infinite orthogonal rewriting unifying our earlier work on
infinite term rewriting and infinite lambda calculus. Confluence in
the infinitary setting is significantly harder than in the finitary
case. The technique of transfinite tiling diagrams in the confluence
proof is new. Infinitary extensions of confluent finite systems may
not be confluent, unless one adds a rule that identifies "meaningless"
terms by reducing them to bottom. Then the extensions become confluent
and normalising; the sets of their normal forms can give new
denotational semantics of the original finite systems.
M. DezaniCiancaglini, P. Severi and F.J. de Vries.
Infinitary Lambda Calculus and
Discrimination of Berarducci trees.
Theoretical Computer Science 298(2):275  302, 2003.
dvi, ps and pdf
AbstractTree semantics of lambda calculus induce equality relations on lambda terms.
For the common tree semantics various authors have given
alternative characterisations in the form of observational equivalence of
suitable extensions of lambda calculus. Berarducci trees are a recent tree
semantics. The induced equality relation is included in all equality relations
induced by a tree semantics. In this paper we give such a
characterisation for Berarducci trees. To do so we make an essential use of our
recently developed techniques for infinite rewriting.
P. Severi and F.J. de Vries.
An Extensional Böhm
Model.
Conference paper in Sophie Tison, editor, Rewiting Techniques and
Applications, Proceedings of the 13th International Conference,
RTA 2002, Copenhagen Denmark, July 2002. (Lecture Notes
in Computer Science 2378), SpringerVerlag. Page 159173. 2002.
dvi, ps and pdf (15 pages)
Abstract Here we present the first confluent and normalising infinitary
extension of extensional lambda calculus using transfinite tiling
diagrams from [Kennawayde Vries 2003]. This requires new infinitary
commutation and postponement results for eta reduction and betabottom
reduction. Application: the set of normal forms of the extension is a
simple (i.e.,\ not using Barendregt's continuity techniques)
description of Barendregt and Dezani's extensional etaBöhm tree model
and gives us a simple and direct (no detour via a Dinfinity
semantics!) syntaxbased proof that two lambda terms are equal in this
model if and only if they are observationally equivalent wrt to
etabeta normal forms.
S. van Bakel, F. Barbanera, M. DezaniCiancaglini, F.J. de
Vries.
Intersection Types for Lambda
Trees.
Theoretical Computer Science 272(12): 340, 2002.
ps and pdf (42 pages)
Abstract Trees have been used to give syntaxflavoured semantics to lambda calculus. As
such they play an important role in the understanding of lambda calculus. In
this paper we study five families of trees and we present an intersection type
assignment system parametric with respect to these five families. Then we
prove, in an (almost) uniform way, that each type assignment system fully
describes the observational equivalence induced by the corresponding tree
representation of lambda terms. For two families of extensional trees this
gives new results and, for the other families of trees, this unifies and
improves earlier results.
M. DezaniCiancaglini, P. Severi and F.J. de Vries.
Böhm's theorem for Berarducci
trees.
In Proceedings CATS 2000 Computing: the Australasian Theory
Symposium, Canberra, Australia, February 12, 2000. Electronic
Notes in Theoretical Computer Science, volume 31, 24 pages,
2000.
dvi (24 pages)
J.R. Kennaway, V. van Oostrom, F.J. de Vries.
Meaningless terms in
rewriting.
Journal of Logic and Functional Programming. The MIT Press.
Article 1, 35 pages. Volume 1999.
dvi, ps and pdf (35 pages)
Abstract We present an axiomatic approach to the concept of meaninglessness in
finite and transfinite term rewriting and lambda calculus. We
justify our axioms in several ways. They can be intuitively
justified from the viewpoint of rewriting as computation. They are
shown to imply important properties of meaninglessness: genericity
of the class of meaningless terms, confluence modulo equality of
meaningless terms, the consistency of equating all
meaningless terms, and the construction of Böhm trees and models
of rewrite systems. Finally, we show that they can be easily
verified for many existing notions of meaninglessness, and easily
refuted for some notions that are known not to be good
characterisations of meaninglessness.
F. Barbanera, M. DezaniCiancaglini, F.J. de Vries.
Types for trees.
In Proceedings IFIP Working Conference on Programming Concepts and
Methods (PROCOMET '98), Shelter Island, New York, Chapman and
Hall, pages 629, 1998.
J.R. Kennaway, J.W. Klop, M.R. Sleep, F.J. de Vries.
Infinitary lambda
calculus.
Theoretical Computer Science 175(1):93125, 1997.
dvi, ps and pdf (38 pages)
Abstract In a previous paper we have established the theory
of transfinite reduction for orthogonal term rewriting systems.
In this paper we perform the same task for the lambda calculus.
From the viewpoint of infinitary rewriting,
the Böhm model of the lambda calculus can be seen as an infinitary
term model.
In contrast to term rewriting,
there are several different possible notions of infinite term,
which give rise to different Böhmlike models,
which embody different notions of lazy or eager computation.
F.J. de Vries.
Böhm trees, bisimulations and
observations in lambda calculus.
In Proceedings of the Second Fuji International Workshop on
Functional and Logic Programming Workshop Shonan Village Center,
Japan 14 November 1996. Editors: T. Ida, A. Ohori and M. Takeichi.
World Scientific, Singapore, pages 230245, 1997.
J.R. Kennaway, J.W. Klop, M.R. Sleep and F.J. de Vries.
Comparing curried and uncurried rewrite
systems.
Journal of Symbolic Computation, 21(1):1539, 1996.
dvi, ps and pdf (25 pages)
J.R. Kennaway, V. van Oostrom, F.J. de Vries.
Meaningless terms in
rewriting.
In Proceedings of the Fifth International Conference on Algebraic
and Logic Programming Aachen (Germany), September 2527, 1996.
Series: Lecture Notes in Computer Science 1139, SpringerVerlag,
pages 254268, 1996.
J.R. Kennaway, J.W. Klop, M.R. Sleep, F.J. de Vries.
Infinite lambda calculus and Böhm
models.
In Proceedings Rewriting Techniques and Applications,
Kaiserslautern, 1995. Series: Lecture Notes in Computer Science
914, SpringerVerlag, pages 257270, 1995.
J.R. Kennaway, J.W. Klop, M.R. Sleep, F.J. de Vries.
From Finite to Infinite Lambda
Calculi.
Bulletin of the section of Logic, University of Lodz, Department of
Logic (Special issue dedicated to the Workshop on Nonstandard
Logics and Logical Aspects of Computer Science, Kanazawa, Japan,
Dec. 58. 1994, editor Hiroakira Ono), 24(1)1320, 1995.
pdf (8 pages)
Abstract
In a previous paper we have established the theory of transfinite reduction for
orthogonal term rewriting systems. In this paper we perform the same task for
the lambda calculus. This results in several new Bohm models of the lambda
calculus and new unifying descriptions of existing models.
D.J.N van Eijck and F.J. de Vries.
Reasoning about Update
Logic.
Journal of Philosophical Logic, 24(1):1947, 1995.
dvi, ps and pdf (19 pages)
E. Horita and F.J. de Vries. A fully abstract denotational
model for communicating processes with labelpassing. In
Proceedings of Concurrency Theory and Its Application,
RIMS Kokyuroku 902, page 2648, 1995.
J.R. Kennaway, J.W. Klop, M.R. Sleep and F.J. de Vries.
Transfinite Reductions in Orthogonal Term
Rewriting Systems.
Information and Computation, 119(1):1838, 1995.
ps and pdf (36
pages)
Abstract We define the notion of transfinite term rewriting:
rewriting in which terms may be infinitely large
and rewrite sequences may be of any ordinal length.
For orthogonal rewrite systems,
some fundamental properties known in the finite case
are extended to the transfinite case.
Among these are the Parallel Moves lemma
and the Unique Normal Form property.
The transfinite ChurchRosser property fails in general,
even for orthogonal systems,
including such wellknown systems as Combinatory Logic.
Syntactic characterisations are given of some classes of orthogonal
TRSs which do satisfy the transfinite ChurchRosser property.
We also prove a weakening of the transfinite ChurchRosser property for all orthogonal systems,
in which the property is only required to hold
up to a certain equivalence relation on terms.
Finally, we extend the theory of needed reduction from the finite
to the transfinite case.
The reduction strategy of needed reduction is normalising in the finite case,
but not in the transfinite case.
To obtain a normalising strategy,
it is necessary and sufficient to add a requirement of fairness.
Parallel outermost reduction is such a strategy.
Z. Ariola, J.R. Kennaway, J.W. Klop, M.R. Sleep and F.J. de
Vries.
On defining the
undefined.
In the proceedings: TACS'94 (Theoretical Aspects of Computer
Software) International conference in Sendai. Series: Lecture Notes
in Computer Science 789, SpringerVerlag, pages 543554,
1994.
J.R. Kennaway, J.W. Klop, M.R. Sleep and F.J. de Vries.
On the Adequacy of Graph Rewriting for
Simulating Term Rewriting.
Transactions on Programming Languages and Systems, 16(3):493523,
1994.
ps (29 pages), pdf
F.J. de Vries and J. Yamada.
On termination of rewriting with real
numbers.
In proceedings: Functional Programming II, JSSST'94.
Editor Masato Takeichi. Series: Lecture Notes on Software Gaku 10.
Publisher: Kindaikagakusya, Tokyo. Pages 233247, 1994.
ps (18 pages), pdf (18 pages) and Addendum (Oct 13, 2004)
J.R. Kennaway, J.W. Klop, M.R. Sleep and F.J. de Vries.
An Introduction to Term Graph
Rewriting.
Chapter 1 in M.R. Sleep, M.J. Plasmeijer and M.C. van Eekelen, editors, Term
Graph Rewriting: Theory and Practice, John Wiley ™Sons Ltd,
pages 113, 1993.
J.R. Kennaway, J.W. Klop, M.R. Sleep and F.J. de Vries.
An infinitary ChurchRosser property for
noncollapsing orthogonal term rewriting systems.
Chapter 4 in M.R. Sleep, M.J. Plasmeijer and
M.C. van Eekelen, editors, Term Graph Rewriting: Theory and
Practice, John Wiley ™ Sons Ltd, pages 4759, 1993.
J.R. Kennaway, J.W. Klop, M.R. Sleep and F.J. de Vries.
Event Structures and Orthogonal Term Graph
Rewriting.
Chapter 11 in M.R. Sleep, M.J. Plasmeijer and M.C. van Eekelen, editors, Term
Graph Rewriting: Theory and Practice, John Wiley ™Sons Ltd,
pages 141155, 1993.
J.R. Kennaway, J.W. Klop, M.R. Sleep and F.J. de Vries.
On the adequacy of graph rewriting for
simulating term rewriting.
Chapter 12 in M.R. Sleep, M.J. Plasmeijer and M.C. van Eekelen, editors, Term
Graph Rewriting: Theory and Practice, John Wiley ™ Sons Ltd,
pages 157169, 1993.
D.J.N van Eijck and F.J. de Vries.
Dynamic interpretation and Hoare
deduction.
Journal of Logic, Language and Information, 1(1):144, 1992.
dvi, ps and pdf (43 pages)
D.J.N van Eijck and F.J. de Vries.
Dynamic interpretation and Hoare deduction
(Extended Abstract).
In S. Moore and A.Z. Wyner, editors, Proceedings of
Semantics and Linguistic Theory, SALT I, CLC Publications, Cornell University, Ithaca,
N.Y., 10:6585, 1991.
J.R. Kennaway, J.W. Klop, M.R. Sleep and F.J. de Vries.
Transfinite reductions in orthogonal term
rewriting systems.
In R.V. Book, editor, Proceedings of Rewriting Techniques and
Applications, Como, Lecture Notes in computer Science 488, pages
112, 1991.
pdf (12 pages)
F.J. de Vries.
Type theoretical topics in topos
theory.
PhD Thesis, University of Utrecht, April 13, 1989. Supervisor Prof
D. van Dalen.
D. van Dalen and F.J. de Vries.
Intuitionistic Free Abelian
Groups.
Zeitschrift für Mathematischen Logik und Grundlagen der
Mathematik, 34(1):312, 1988.
F.J. de Vries.
A functional program for the Fast Fourier
Transform.
SigmaPlan Notices, 23(1):6774, 1988.
J. Giesl, J.R, V. van Oostrom, F.J. de Vries. Strong
convergence of term rewriting using strong dependency pairs.
Extended abstract. In Proceedings of Termination Workshop, Schloss
Dagstuhl, 1999.
pdf (2 pages plus erratum)
F.J. de Vries. Projection spaces and recursive domain
equations. Information Processing Society of Japan SIG Notes. 95(114):3738, 1995
.
J.R. Kennaway, J.W. Klop, M.R. Sleep and F.J. de Vries. From
finite lambda calculus to infinite lambda calculi (abstract)
Information Processing Society of Japan, SIG Notes
94PRG196:4350, 1994.
J.R. Kennaway, J.W. Klop, M.R. Sleep and F.J. de Vries.
On comparing curried and uncurried
rewrite systems. In H.P. Barendregt, M. Bezem and J.W. Klop,
editors, Festschrift dedicated to the sixtieth anniversary of Dirk
van Dalen, Quaestiones Infinitae, Logic Series, Department of
Philosophy, University of Utrecht, pages 5778, 1993.
P. Severi and F.J. de Vries.
A lambda calculus for
Dinfinity.
Presented at the Workshop at Domain Theory held at the honour
of Dana Scott's 70th birthday.
Technical Report tr200229, University of Leicester, June
2002.
dvi (10 pages),
ps (10 pages)
Abstract We define an extension of lambda
calculus which is fully abstract for Scott's Dinfinity models. We
do so by constructing an infinitary lambda calculus which not only
has the confluence property, but also is normalising: every term
has its infetaBöhm tree as unique normal form. The extension
incorporates a strengthened form of etareduction besides infinite
terms, infinite reductions and a bottom rule allowing to replace
terms without head normal form by bottom. The new eta!reduction is
the key idea of this paper. It allows us to capture in a compact
and natural way Barendregt's complex infinite etaoperation on
Böhm trees. As a corollary we obtain a new congruence proof
for Böhm tree equivalence modulo infinite
etaexpansion.
P. Severi and F.J. de Vries.
An Extensional Böhm
Model.
In the Proceedings of RTA'02, Springer Lecture Notes in Computer Science 2378.
Technical Report tr200228, University of Leicester, June
2002.
dvi (15 pages),
ps (15 pages)
Abstract We show the existence of an infinitary
confluent and normalising extension of the finite extensional
lambda calculus with beta and eta. Besides infinite beta reductions
also infinite eta reductions are possible in this extension, and
terms without head normal form can be reduced to bottom. As
corollaries we obtain a simple, syntax based construction of an
extensional Böhm model of the finite lambda calculus; and a
simple, syntax based proof that two lambda terms have the same
semantics in this model if and only if they have the same
etaBöhm tree if and only if they are observationally
equivalent wrt to beta normal forms. The confluence proof reduces
confluence of beta, bottom and eta via infinitary commutation and
postponement arguments to confluence of beta and bottom and
confluence of eta. We give counterexamples against confluence of
similar extensions based on the identification of the terms without
weak head normal form and the terms without top normal form
(rootactive terms) respectively.
S. Byun, J.R. Kennaway, V. van Oostrom, F.J. de Vries.
Separability and translatability of
sequential term rewrite systems into the lambda
calculus.
Technical Report tr200116, University of Leicester, April
2001.
dvi (35 pages),
ps (35 pages)
Abstract Orthogonal term rewrite systems do not
currently have any semantics other than syntacticallybased ones
such as term models and event structures. For a functional language
which combines lambda calculus with term rewriting, a semantics is
most easily given by translating the rewrite rules into lambda
calculus and then using wellunderstood semantics for the lambda
calculus. We therefore study in this paper the question of which
classes of TRSs do or do not have such translations. We demonstrate
by construction that forward branching orthogonal term rewrite
systems are translatable into the lambda calculus. The translation
satisfies some strong properties concerning preservation of
equality and of some inequalities. We prove that the forward
branching systems are exactly the systems permitting such a
translation which is, in a precise sense, uniform in the righthand
sides. Connections are drawn between translatability, sequentiality
and separability properties. Simple syntactic proofs are given of
the nontranslatability of a class of TRSs, including Berry's F and
several variants of it.
J.R. Kennaway and F.J. de Vries.
Infinitary Rewriting.
Technical Report tr200113, University of Leicester, March
2001.
dvi (48 pages),
ps (48 pages)
Abstract In this chapter we will give the basic
definitions and properties of infinite terms and infinite reduction
sequences, for both term rewrite systems and the lambda calculus.
We will then study confluence properties in orthogonal systems,
which turns out to be significantly more complicated than in the
finitary case. In general, these systems are only confluent up to
an identification of a certain class of terms. The breakdown of
confluence leads us to consider the concept of a meaningless term,
which further suggests a link with the lambdacalculus concept of
Böhm reduction, and to denotational semantics for
TRSs.
M. DezaniCiancaglini, P. Severi and F.J. de Vries.
Infinitary Lambda Calculus and
Discrimination.
Technical Report tr200106, University of Leicester, February
2001.
dvi (33 pages),
ps (33 pages)
Abstract We propose an extension of lambda
calculus for which the Berarducci trees equality coincides with
observational equivalence, when we observe rootstable or rootactive
behavior of terms. In one direction the proof is an adaptation of
the classical Böhm out technique. In the other direction the
proof is based on confluence for strongly converging reductions in
this extension.
J.R. Kennaway, V. van Oostrom, F.J. de Vries. Meaningless
terms in rewriting, revised version. Technical Report: Utrecht
Universiteit, Artificial Intelligence Preprint Series No: 003, May,
1999.
F. Barbanera, M. DezaniCiancaglini, F.J. de Vries. Types
for Trees. Technical Report: Dipartimento di Unformatica,
Universita' di Torino, 1997.
J.R. Kennaway, V. van Oostrom, F.J. de Vries. Meaningless
terms in rewriting Technical Report: Vrije Universiteit,
Amsterdam, IR418, 23 pages, January, 1997.
J.R. Kennaway, J.W. Klop, M.R. Sleep, F.J. de Vries.
Infinite lambda calculus, Report CSR9535, CWI, Amsterdam,
1995.
E. Horita and F.J. de Vries. A fully abstract denotational
model for communicating processes with labelpassing. ECL
Technical Report. NTT Kyoto, 1994.
J.R. Kennaway, J.W. Klop, M.R. Sleep, F.J. de Vries. On
comparing curried and uncurried rewrite systems. Revised
version of Festschrift version. Report CSR9350, CWI, Amsterdam,
1993.
D.J.N. van Eijck and F.J. de Vries. Reasoning about Update
Logic, (Completely revised version of report CSR9155), Report
CSR9312, CWI, Amsterdam, 1993.
Kennaway J.R., Klop J.W., Sleep M.R., Vries F.J. de,
Transfinite reductions in orthogonal term rewriting systems,
Report SYSC9310, School of Information Systems, Univ. of East
Anglia, Norwich, England. Revised version of 17.
J.R. Kennaway, J.W. Klop, M.R. Sleep, F.J. de Vries. On the
Adequacy of Graph Rewriting for Simulating Term Rewriting,
Report CS9204, CWI, Amsterdam, 1992. Similar as 10.
J.R. Kennaway, J.W. Klop, M.R. Sleep, F.J. de Vries. On the
Adequacy of Graph Rewriting for Simulating Term Rewriting,
Report IR287, Vrije Universiteit Amsterdam.
D.J.N. van Eijck and F.J. de Vries. A sound and complete
calculus for Update Logic, report CSR9155, CWI, Amsterdam,
1991.
J.R. Kennaway, J.W. Klop, M.R. Sleep, F.J. de Vries. Event
structures and orthogonal term graph rewriting, in M.J.
Plasmeijer and M.R. Sleep, editors, Sema Graph '91, Part II,
Technical Report 9125, Department of Informatics, University of
Nijmegen, 1991.
J.R. Kennaway, J.W. Klop, M.R. Sleep, F.J. de Vries. Finite
orthogonal graph rewriting is adequate for rational orthogonal term
rewriting, in M.J. Plasmeijer and M.R. Sleep, editors, Sema
Graph '91, Part I, Technical Report 9125, Department of
Informatics, University of Nijmegen, 1991.
D.J.N. van Eijck and F.J. de Vries. Dynamic interpretation
and Hoare deduction, report CSR9115, CWI, Amsterdam,
1991.
J.R. Kennaway, J.W. Klop, M.R. Sleep, F.J. de Vries. An
infinitary ChurchRosser property for noncollapsing orthogonal
term rewriting systems, report CSR9043, CWI, Amsterdam,
1990.
pdf
J.R. Kennaway, J.W. Klop, M.R. Sleep, F.J. de Vries.
Transfinite reductions in orthogonal term rewriting systems
(Extended abstract), report CSR9042, CWI, Amsterdam,
1990.
pdf (somewhat corrupted font)
J.R. Kennaway, J.W. Klop, M.R. Sleep, F.J. de Vries.
Transfinite reductions in orthogonal term rewriting systems
(Full version) , report CSR9041, CWI, Amsterdam, 1990.
.
pdf (47 pages)
A. Ponse and F.J. de Vries. Strong completeness for Hoare
Logics of Recursive Processes: an infinitary approach, report
CSR8957, CWI, Amsterdam, 1989.
F.J. de Vries. Applications of constructive logic to sheaf
constructions in toposes, Logic Group Preprint Series No. 25,
Department of Philosophy, University of Utrecht, October 1987.
F.J. de Vries. A functional program for Gaussian
elimination, Logic Group Preprint Series No. 23, Department of
Philosophy, University of Utrecht. September 1987.
F.J. de Vries. A functional program for the Fast Fourier
Transform, Logic Group Preprint Series No. 19, Department of
Philosophy, University of Utrecht, April 1987.
D. van Dalen and F.J. de Vries. Intuitionistic Free Abelian
Groups, Logic Group Preprint Series No. 7, Department of
Philosophy, University of Utrecht, April 1986.
F.J. de Vries. Type theory with a geometric modality and
extensions of the reals, Preprint 340, Mathematical Institute,
University of Utrecht, June 1984.
Review of Algebra in a localic topos, with applications to
ring theory by F.Borceux and G. van den Bossche, Nov 1985,
Mededelingen van het Wiskundig Genootschap.
Review of Antimorphic action by W.H. Cornish, 1988,
Mededelingen van het Wiskundig Genootschap.
Review of Graphgrammars and their application to computer
science by H.Ehrig, e.a. (eds), 1990, Informatie.
Review of Cartesian closed categories of domains by A.
Jung, 1990, Mededelingen van het Wiskundig Genootschap.

