Streams Seminar

Nijmegen

After ten successful meetings in 2010, the streams seminar will be continued in 2011. It is organized by Herman Geuvers, Jan Willem Klop, Jan Rutten and Hans Zantema, at the Radboud University Nijmegen (in between the two streams Maas and Waal).

The meetings will be in the Huygens gebouw, Heyendaalseweg 135, Nijmegen How to get there?

Presentations in 2011:

date	time	room	speaker	title
Tuesday, January 25, 2011	13:30 - 15:30	HG02.032	Wieb Bosma	Automatic sequences slides
Tuesday, February 22, 2011	10:30 - 11:15	HG00.023	Frits Dannenberg	On Toeplitz substitutions and transducer equivalence abstract
	11:30 - 12:30	HG00.023	Frank Staals	Stream equality in Coq
Tuesday, May 10, 2011	13:30 - 14:30	HG02.028	Rudolf Mak (TU/e)	Periodic-Drop-Take Calculus for Stream Transformers slides
	14:30 - 15:30	HG02.028	Joost Winter (CWI)	Context-free languages and streams slides

Abstract of presentation on May 10 by Rudolf Mak:
Stream transformers are a formalism to specify and reason about stream processing systems. Many application specific circuits, e.g. in the area of digital signal processing , classify as such systems. We present a two operator calculus to reason about a specific class of stream operators, viz. the periodic stream samplers. The calculus is sound and complete and an algorithm using only a few rules is given to bring each operator sequence in canonical form. As an example, we apply the calculus to show FIFO behavior of a class of circuits built from three simple components exhibiting repetitive behavior. In addition, we briefly discuss an extended version of the calculus suitable to reason about linear filters. Also the usage of the calculus for periodic scheduling purposes is sketched.



The meetings are open to both students and researchers. Suggestions for talks will be welcome.

The subject:

A stream over a data set A is an infinite sequence of elements from A, that is, a mapping from the natural numbers to A.

Streams form the simplest data type in which the objects themselves are infinite. Thus arises the issue of representation: where finite objects can be described by their syntax, for infinite objects such as streams, we need finite representations, together with notions of equality to state that two finite representations represent the same infinite object.

Where the natural numbers form one of the simplest (initial) algebras where an induction principle comes in, streams form a canonical example of a (final) co-algebra for which a co-induction principle holds. Thus streams form a fundamental data structure for which a basic understanding is worthwhile.

The foundations of streams will be studied and discussed from several different perspectives, including term rewriting and co-algebra. Also, we shall be interested in understanding streams in the various contexts where they are applied, in both computer science and mathematics. Examples include semantics, data flow, signal processing, analysis, real number arithmetic. Finally, tools supporting automated reasoning about streams will have our attention too.

The last years have seen several new developments in defining and understanding streams, amongst others in the context of the NWO/BRICKS project INFINITY, a collaboration of the Free University in Amsterdam, Utrecht University and CWI, and in the context of the Foundations group at the Radboud University in Nijmegen.

Past presentations in 2010:

date	time	room	speaker	title
Monday, January 18	14:00 - 14:50	HG01.058	Jan Rutten	Streams from a co-algebraic perspective slides
Monday, January 18	15:10 - 16:00	HG01.058	Helle Hansen	Stream functions from a co-algebraic perspective slides
Monday, February 22	14:00 - 16:00	HG00.058	Hans Zantema	Streams from a rewriting perspective slides
Monday, March 15	14:00 - 16:00	HG00.062	Herman Geuvers	Streams in Coq slides
Tuesday, April 20	13:30 - 15:30	HG01.058	Dimitri Hendriks, Joerg Endrullis, Jan Willem Klop	Classifying streams slides JWK, slides DH, slides JE
Monday, May 17	14:00 - 16:00	HG02.028	Peter Hancock (MSFP, Strathclyde Univ. Scotland)	Streams from a type-theoretic perspective slides
Monday, June 21	14:00 - 16:00	HG02.028	Bas Spitters	Quantification over streams
Monday, September 6	13:30 - 14:30	HG00.065	Jan Rutten	Stream differential equations
Monday, September 6	14:30 - 15:30	HG00.065	Milad Niqui	Streams in Coq
Monday, October 4	13:30 - 15:30	HG00.065	Joerg Endrullis and Hans Zantema	Proving equality of streams automatically
Monday, November 1	13:30 - 15:30	HG00.065	Herman Geuvers	Representations of real numbers slides
Tuesday, November 30	13:30 - 14:30	HG02.032	Wouter Swierstra	Stream Fusion slides

Last change: May 11, 2011