Offentlige arrangementer
Bemærk at IT-Forums arrangementer ikke er offentlige men kun for medlemmer. Aarhus Universitet er medlem af IT-Forum, hvilket betyder at medarbejdere samt de studerende der har specielle interesser i specifikke arrangementer, pg.a. opgaveskrivning inden for emnet, derfor kan komme gratis ind. Andre skal betale for det.
| 30.10.2008 |
PL-Seminar Talk: Olivier Danvy |
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We derive two big-step abstract machines, a natural semantics, and the valuation function of a denotational semantics based on the small-step abstract machine for Core Scheme presented by Clinger at PLDI'98. Starting from a functional implementation of this small-step abstract machine, (1) we fuse its transition function with its driver loop, obtaining the functional implementation of a big-step abstract machine; (2) we adjust this big-step abstract machine so that it is in defunctionalized form, obtaining the functional implementation of a second big-step abstract machine; (3) we refunctionalize this adjusted abstract machine, obtaining the functional implementation of a natural semantics in continuation style; and (4) we closure-unconvert this natural semantics, obtaining a compositional continuation-passing evaluation function which we identify as the functional implementation of a denotational semantics in continuation style. We then compare this valuation function with that of Clinger's original denotational semantics of Scheme.
Presented at the 2008 Workshop on Scheme and Functional Programming, Victoria, BC, September 2008.
In preparation for the talk, it would be a good idea to look again at Will Clinger's denotational semantics of Scheme and at his PLDI'98 paper.
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| Tid/sted |
kl. 15.15 til 16.45 - Turing-014 |
| Info |
http://www.cs.au.dk |
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| 31.10.2008 |
PL-seminar talk: Chung-chieh Shan |
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Shifting the Stage: Staging with Delimited Control Chung-chieh Shan (joint work with Yukiyoshi Kameyama and Oleg Kiselyov)
It is often hard to write programs that are efficient yet reusable. For example, an efficient implementation of Gaussian elimination should be specialized to the structure and known static properties of the input matrix. The most profitable optimizations, such as choosing the best pivoting or memoization, cannot be expected of even an advanced compiler because they are specific to the domain, but expressing these optimizations directly makes for ungainly source code. Instead, a promising and popular way to reconcile efficiency with reusability is for a domain expert to write code generators.
Two pillars of this approach are types and effects. Typed multilevel languages such as MetaOCaml ensure _safety_: a well-typed code generator neither goes wrong nor generates code that goes wrong. Side effects such as state and control ease _correctness_: an effectful generator can resemble the textbook presentation of an algorithm, as is familiar to domain experts, yet insert _let_ for memoization and _if_ for bounds-checking, as is necessary for efficiency. However, adding effects blindly renders multilevel types unsound.
We introduce the first two-level calculus with control effects and a sound type system. We give small-step operational semantics as well
as a continuation-passing style (CPS) translation. For soundness,
our calculus restricts the code generator's effects to the scope of
generated binders. Even with this restriction, we can finally write
efficient code generators for dynamic programming and numerical methods
in direct style, like in algorithm textbooks, rather than in CPS or
monadic style.
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| Tid/sted |
kl. 10.00 til 11.00 - Turing-014 |
| Info |
http://www.cs.au.dk |
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| 31.10.2008 |
Forandringsledelse ved implementering af komplekse informationssystemer |
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Forelæsningen vil fokusere på såvel teoretiske som praktiske aspekter ved forandringsledelse i forbindelse med implementering af komplekse informationssystemer. Der indledes med en oversigt over organisationsteorier og deres sammenhæng til forandringsledelse. Herefter vil en række modeller til forandringsledelse blive gennemgået mere detaljeret, og de vil blive relateret til et praktisk eksempel med implementering af et CRM system i en større dansk servicevirksomhed. Såfremt tiden tillader det, så vil Pers forskningsprojekt vedrørende "virksomhedssystemer jomfrurejse" blive berørt, hvor institutionel teori anvendes som teoretisk linse.
Per er ansat på Handelshøjskolen, Aarhus Universitet er ph.d.-stipendiat og forsker i sammenhængen mellem virksomhedssystemer og organisationer. Per er endvidere medejer af ProConsulting, som arbejder med rådgivning og konsulentbistand inden for projektledelse og forandringsledelse. Per har ca. 25 års praktisk erfaring med projektledelse og er IPMA certificeret seniorprojektleder. Per har en baggrund som cand.it og ingeniør. |
| Tid/sted |
kl. 14:15 - Lille Auditorium |
| Info |
http://www.imv.au.dk |
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| 04.11.2008 |
Er netværk for folket eller er netværk for fjollet? |
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Samfundet udvikler sig i en retning, hvor freelance-virksomheder og projektansættelser breder sig, og vi skifter jobs hurtigere, end træerne skifter blade. Allerede nu er dit professionelle netværk en af de faktorer, du bliver ansat på. Arbejdspladserne foregår, netværket består.
Hvem kender du? Undersøgelser viser, at du som studerende hovedsageligt kender andre studerende. Er dit netværk det bedste til at hjælpe dig til dit første job, eller til hvor man finder den bedste café latte? Hvad skal du gøre for, at dit netværk bliver til din fordel? Hvordan bliver du en netværker, der har stort udbytte af dit netværkspotentiale. fordi andre med glæde hjælper dig frem. |
| Tid/sted |
kl. 14.00 til 16.30 - Center for Entrepreneurship, Finlandsgade 25 |
| Info |
http://www.katrinebjerg.net |
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| 04.11.2008 |
CAGT Seminar: Orestis Telelis |
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Title: On Pure and (approximate) Strong Equilibria of Facility Location Games
We study social cost losses in Facility Location games, where n selfish agents install facilities over a network and connect to them, so as to forward their local demand (expressed by a non-negative weight per agent). Agents using the same facility share fairly its installation cost, but every agent pays individually a (weighted) connection cost to the chosen location. We study the Price of Stability (PoS) of pure Nash equilibria and the Price of Anarchy of strong equilibria (SPoA), that generalize pure equilibria by being resilient to coalitional deviations. For unweighted agents on metric networks we prove upper and lower bounds on P oS, while an O(ln n) upper bound implied by previous work is tight for non- metric networks. We also prove a constant upper bound for the SPoA of metric networks when strong equilibria exist. For the weighted game on general networks we prove existence of e-approximate (e = 2.718...) strong equilibria and an upper bound of O(ln W) on SPoA (W is the sum of agents weights), which becomes tight (ln n) for unweighted agents.
Joint work with Thomas Dueholm Hansen. |
| Tid/sted |
kl. 14.15 til 15.15 - Turing-14 |
| Tilmeldning |
http://www.cs.au.dk |
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| 05.11.2008 |
PL-Seminar talk: Olivier Danvy |
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Title: Towards compatible and interderivable semantic specifications for the Scheme programming language, part II: reduction semantics and abstract machines
We present a context-sensitive reduction semantics for a lambda-calculus with explicit substitutions and store and we show that the functional implementation of this small-step semantics mechanically corresponds to an abstract machine. This abstract machine is very close to the abstract machine for Core Scheme presented by Clinger at PLDI'98. This lambda-calculus with explicit substitutions and store therefore aptly accounts for Core Scheme.
Presented at the 2008 Workshop on Scheme and Functional Programming, Victoria, BC, September 2008.
Joint work with Malgorzata Biernacka. |
| Tid/sted |
kl. 9:30 til 10:30 - Turing-014 |
| Info |
http://www.cs.au.dk |
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