Jamie Andrews | 1 Jun 03:39 2002

Re: Imperative structure-copying languages?

     Thanks to all for the interesting recent discussion on C
semantics.  There are still a lot of problems with C-like
languages, many of them having to do with pointer aliasing.
Pointer aliasing makes semantics more difficult to specify and
analysis more difficult to do.  Pure functional languages are
nicer wrt pointer aliasing, but a lot of people don't seem to
want to switch to them.

     A reasonable compromise might be imperative languages with
no destructive pointer aliasing.  What I mean by that is
imperative languages in which two pointers A and B can point to
the same object, but in which it is impossible for an update to
A to affect what pointer B points to.  This would presumably be
implemented by some sort of partial structure copying.

     The kind of algorithms we could write in such languages
would be the same as the kind we could write in functional
languages, with similar efficiency, just expressed using
imperative language constructs.  This may prompt the thought
that if people don't use functional languages, they won't use
such languages either.  On the other hand, if someone had told
me 10 years ago that we would now have a very well-established
language which is imperative but does garbage collection and
uses type tags on data structures, I don't know if I would have
believed it.  Maybe imperative structure-copying languages are
the way of the future.

     The ideas that follow are probably half-baked versions of
well-known research, so please save me the further embarrassment
of continuing to erroneously re-state the obvious and let me
(Continue reading)

Jim Royer | 1 Jun 05:35 2002

Preliminary program for the Implicit Complexity Workshop (ICC'02)

The Implicit Complexity Workshop (ICC'02) will be held on 20-21 July
2002 in Copenhagen.

ICC'02 is part of the Federated Logic Conference (FLOC'02) and
affiliated with the IEEE Symposium on Logic in Computer Science
(LICS 2002). 


==== Saturday July 20th ================================================

11:00-12:30  SESSION 1

 11:00 Paul J. Voda, Comenius U, Slovakia
         Program committee talk: Two simple intrinsic characterizations
         of main complexity classes 
 12:00 Olivier Bournez, Paulin de Naurois, and Jean-Yves Marion; LORIA
       Nancy, France 
         Safe recursion and calculus over an arbitrary structure

12:30-14:00  LUNCH

14:00-15:30  SESSION 2

 14:00 Carl Christian Frederiksen and Neil D. Jones, DIKU, U
         Program committee talk: Program analysis for implicit
         computational complexity 
 15:00 Lars Kristiansen, Oslo U College, Norway
(Continue reading)

Ruy de Queiroz | 1 Jun 15:34 2002

WoLLIC'2002 - Call for Participation

                         Call for Participation

        9th Workshop on Logic, Language, Information and Computation
                        July 30 to August 2, 2002

           Scientific Co-Sponsorship: IGPL, FoLLI, ASL, SBC, SBL

                        Rio de Janeiro, Brazil

	"Electronic Notes in Theoretical Computer Science" (Elsevier))

  The "9th Workshop on Logic, Language, Information and Computation"
  (WoLLIC'2002), the nineth version of a series of workshops which started
  in 1994 with the aim of fostering interdisciplinary research in pure and
  applied logic, will be held in Rio de Janeiro, Brazil, from July 30 to
  August 2, 2002.

  Contributions will be presented in the form of short papers in
  all areas related to logic, language, information and computation, including:
  pure logical systems, proof theory, model theory, algebraic logic, type
  theory, category theory, constructive mathematics, lambda and combinatorial
  calculi, program logic and program semantics, logics and models of
  concurrency, logic and complexity theory, proof complexity,
  foundations of cryptography (zero-knowledge proofs), descriptive complexity,
  nonclassical logics, nonmonotonic logic, logic and language,
(Continue reading)

Benjamin C. Pierce | 1 Jun 22:17 2002

TYPES on vacation

Your Types moderator will be out of email contact during most of the
next two and a half weeks.  Postings submitted to Types during that
period will be distributed when I return.  (If you were thinking of
posting something and want it distributed sooner, you've got till
Monday afternoon...)



Dept. of Computer & Information Science                bcpierce@...
University of Pennsylvania                                    +1 215 898-2012
200 South 33rd St.                                       Fax: +1 215 898-0587
Philadelphia, PA 19104, USA                http://www.cis.upenn.edu/~bcpierce

Frank Pfenning | 3 Jun 15:56 2002

LFM'02 Program and Call for Participation

		   Program and Call for Participation

		    Third International Workshop on
		 Logical Frameworks and Meta-Languages


		     A FLoC'02 affiliated workshop
		   Copenhagen, Denmark, July 26, 2002

Logical frameworks and meta-languages form a common substrate for
representing, implementing, and reasoning about a wide variety of
deductive systems of interest in logic and computer science.  Their
design and implementation has been the focus of considerable research
over the last two decades, using competing and sometimes incompatible
basic principles.  This workshop will bring together designers,
implementors, and practitioners to discuss all aspects of logical

Informal proceedings will be published as a volume in the Electronic
Notes in Theoretical Computer Science (ENTCS) and will be available
at the workshop.

The workshop is open for any interested party.  If you are planning to
attend you are welcome to participate in the informal system
demonstration session.  Please send mail to the workshop chair (Frank
Pfenning <fp@...>) if you are interested in showing your
(Continue reading)

nipkow | 7 Jun 09:10 2002


			       Call for Papers


		   Special issue on BYTECODE VERIFICATION

The BYTECODE VERIFIER is a component of the Java Virtual Machine (JVM) that
checks assembly language programs ("bytecodes") for wellformedness, thus
guaranteeing certain safety properties. Essentially, the bytecode verifier is
a program analyzer that checks if the program is welltyped, which implies
type safety of the execution. Due to the subtle type system of the JVM, the
correctness of bytecode verification has been an active research area over
the past 5 years.

This special issue will be devoted to the topic of bytecode verification.  It
is not restricted to the JVM but encompasses related approaches to program
analysis of low level code for the enforcement of safety
properties. Particularly welcome are contributions emphasizing

 (i) the correctness of analysis techniques
(ii) the application of automated or interactive verification techniques.

Manuscripts should be unpublished works and not submitted elsewhere.
Revised and enhanced versions of papers published in conference
proceedings that have not appeared in archival journals are eligible
for submission.  All submissions will be reviewed according to the
usual standards of scholarship and originality.  Information on JAR
submissions can be found at http://www-unix.mcs.anl.gov/JAR/.

Submissions should be sent to the guest editor in ps or pdf format.
(Continue reading)

Viktor Kuncak | 8 Jun 22:17 2002

Re: Imperative structure-copying languages?

 >      A reasonable compromise might be imperative languages with
 > no destructive pointer aliasing.  What I mean by that is
 > imperative languages in which two pointers A and B can point to
 > the same object, but in which it is impossible for an update to
 > A to affect what pointer B points to.  This would presumably be
 > implemented by some sort of partial structure copying.

Is your primary difference compared to functional programs:

 1) how we write programs, or
 2) how efficient the programs are?

If it is 1), then it seems one would like a generalization
of record update of Haskell to nested updates.  I believe
this is interesting idea.  It also comes up in declarative
specification languages like Alloy, e.g. for expressing
frame conditions.

If your goal is 2), then this is the question of how to
implement the semantics of value copying.  I believe
copy-on-write techniques have been used in e.g. database
community but I don't know the best reference for that.

I believe that in both cases the critical question is
expressing the invariants of data structures.  There are not
too many patterns of pointer sharing in programming
languages.  For example, neither functional programming
approach nor imperative programming approach directly
support working with trees that are destructively updated,
(Continue reading)

Peter Thiemann | 12 Jun 13:57 2002

TIP'02: Call for Participation

[ATTENTION: date changed!]

			Call for Participation
	      Workshop on Types in Programming (TIP'02)
		   Dagstuhl, Germany, July 8, 2002
			Colocated with MPC'02

Modern programming languages rely on type systems with static type
checking to detect common errors at compile time. While the benefits
of statically checked type systems have long been recognized, there
are some areas where the type systems of modern programming languages
are not expressive enough. Some interesting programs will always be
rejected, despite their semantical soundness.

There are several remedies to this situation, ranging from dependent
types (where types may contain values) through intersection types to
types with modalities. These systems are well-investigated from a
theoretical point of view by logicians and type theorists. However,
the impact of these developments on practical programming has been
small, partly because they are trading simplicity against

The objective of the workshop is to make researchers in programming
languages aware of new developments and research directions on the
theory side while at the same time pointing out problems arising in
practical uses to theorists.  Technical topics include, but are not
limited to:

* Type systems in all variants: polymorphic, dependent, intersection,
(Continue reading)

tony | 13 Jun 14:05 2002

CONCUR'02 Call for Participation

**                                                                       **
**                        C O N C U R    2 0 0 2                         **
**                                                                       **
**                                                                       **
**                        CALL FOR PARTICIPATION                         **
**                                                                       **
**                                                                       **
**      !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!      **
**      !!!!  DO NOT MISS THE EARLY PAYMENT - DUE ON  JULY 8   !!!!      **
**      !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!      **
**                                                                       **
**        The 13th International Conference on Concurrency Theory        **
**                                                                       **
**               August 20-23, 2002, Brno, Czech Republic                **
**                                                                       **
**                   http://www.fi.muni.cz/concur2002/                   **
**                                                                       **

CONCUR 2002, the international conference on concurrency theory, will
be organised by the Faculty of Informatics of Masaryk University in
Brno, Czech Republic. The purpose of the CONCUR conferences is to
bring together researchers, developers and students in order to
advance the theory of concurrency, and promote its
applications. Interest in this topic is continuously growing, as a
consequence of the importance and ubiquity of concurrent systems and
their applications, and of the scientific relevance of their
(Continue reading)

Constraint Programming 2002 | 14 Jun 12:56 2002

CP-2002 Workshop Programme: Call for Contributions and Participation

                     Call for Participation

                       Workshop Programme 
              Eighth International Conference On
       Principles and Practice of Constraint Programming

                     September 7 - 13, 2002
                        Ithaca, NY, USA



  September 8:       Workshop Programme

Please note that this is a tentative schedule. Please check the 
workshop programme page in the future in order to confirm
the schedule.


   CP-2002 workshops will provide an informal setting where workshop
participants will have the opportunity to discuss specific technical
topics in an atmosphere that fosters the active exchange of ideas.
Workshops are an opportunity to disseminate work in progress or
to promote new and emerging areas within the field of constraints.
(Continue reading)