Seminars

Links' Seminars and Public Events Add to google calendar
2019
Thu 19th Dec
11:00 am
1:30 pm
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Thèse L. Gallois

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amphi Bâtiment B Inria
Fri 13th Dec
11:45 am
1:00 pm
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1. On Parsing Gpath (Jérémy and Antonio) 2. On Nested Regular Expression (Joachim)
Fri 13th Dec
10:30 am
11:45 am
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Repet Lily pour l'équipe
"Lille-Salle B31 "
Tue 24th Sep
10:00 am
11:00 am
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Stijn Vansummeren
Title: General Dynamic Yannakakis: Conjunctive Queries with Theta Joins Under Updates
Abstract:
The ability to efficiently analyze changing data is a key requirement
of many real-time analytics applications like Stream Processing,
Complex Event Recognition, Business Intelligence, and Machine
Learning.

Traditional approaches to this problem are based either on the
materialization of subresults (to avoid their recomputation) or on the
recomputation of subresults (to avoid the space overhead of
materialization). Both techniques have recently been shown suboptimal:
instead of fully materializing results and subresults, one can
maintain a data structure that supports efficient maintenance under
updates and can quickly enumerate the full query output, as well as
the changes produced under single updates.

In our work we are concerned with designing a practical family of
algorithms for dynamic query evaluation based on this idea, and for
queries featuring both equi-joins and inequality joins, as well as
certain forms of aggregation. Our main insight is that, for acyclic
conjunctive queries, such algorithms can naturally be obtained by
modifying Yannakakis' seminal algorithm for processing acyclic joins
in the static setting.

In this talk I present the main ideas behind this modfication,
offset it against the traditional ways of doing incremental view
maintenance, and discuss recent extensions such as dealing with
general theta-joins.
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Amphitheater of INRIA Building B.
Tue 25th Jun
11:30 am
5:30 pm
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Happy Hours
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Inria Lille
Tue 25th Jun
10:30 am
11:30 am
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Seminar Véronique Benzaken and Évelyne Contejean
Elles présenteront un outil qui prend en entrée une requête SQL et sa compilation par Postrgres sous forme de plan d'exécution, et démontre (avec Coq) que la requête initiale est équivalente au plan d'exécution.
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Lille-Salle B21
Fri 21st Jun
11:00 am
12:00 pm
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Charles
Fri 24th May
11:00 am
12:00 pm
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Seminaire Sławek
Fri 10th May
11:00 am
12:00 pm
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Seminaire Iovka
Fri 12th Apr
11:00 am
12:30 pm
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Alexandre Vigny in Links Seminar
Fri 5th Apr
11:00 am
12:00 pm
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Semyon Grigorev in Links' seminar
Fri 5th Apr
11:00 am
12:30 pm
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Talk of Semyon Grigorev
Title: Parsing techniques for context-free path querying
Abstract: Context-free path querying (CFPQ) is a case of language constrained path querying: the way to specify constraints on paths in a graph in terms of formal languages. In CFPQ language is restricted to be a context-free. Classical parsing techniques and algorithms, such as generalized LR and LL parsing, or parser combinators, can be used for CFPQ. Results of adaptation of different parsing techniques for CFPQ will be presented.
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B31
Fri 22nd Mar
10:00 am
11:30 am
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Seminar LINKS by Aurelien Lemay "Tutorial: Grammatical Inference"
Fri 8th Mar
11:00 am
12:00 pm
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Seminar Momar
Title: Regular Matching and Inclusion on Compressed Tree Patterns with Context Variables

Abstract: We study the complexity of regular matching and inclusion for compressed tree patterns extended by context variables. The addition of context variables to tree patterns permits us to properly capture compressed string patterns but also compressed patterns for unranked trees with tree and hedge variables. Regular inclusion for the latter is relevant to certain query answering on Xml streams with references.
Fri 15th Feb
11:00 am
12:00 pm
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Seminar [Florent]
Wed 13th Feb
1:30 pm
2:30 pm
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30mn de science : Florent Capelli on Knowledge Compilation

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Inria salle Plénière (Bâtiment A)
Fri 1st Feb
11:00 am
12:30 pm
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Bruno Guillon in Links' seminar
Title: Finding paths in large graphs

Abstract:
When dealing with large graphs, classical algorithms for finding paths such as Dijkstra's Algorithm are unsuitable, because they require to perform too many disk accesses. To avoid this while keeping a data structure of size quasi-linear in the size of the graph, we propose to guide the path search with a distance oracle, obtained from a topological embedding of the graph.
I will present fresh experimental research on this topic, in which we obtain graph embeddings using learning algorithms from natural language processing. On some graphs, such as the graph of publications from DBLP, our topologically-guided path search allows us to visit a small portion of the graph only, in average.
This is joint work with Charles Paperman.
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B21 Room
2018
Fri 23rd Nov
11:00 am
12:30 pm
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Filip Mazowiecki in Links' seminar
Title: Containment for Probabilistic automata.

Abstract: This is an ICALP 2018 paper. We analyze when the model of probabilistic
automata has decidable properties, when restricting the ambiguity. The
notion of ambiguity is usually used in weighted automata or transducers,
but we follow a recent paper by Fijalkow, Riveros and Worrell, which
introduced this approach. We do not solve everything but our decidability
results rely unexpectedly on Schanuel's conjecture and we provide some
geometric intuition behind the hardness of the problem.
Fri 16th Nov
11:00 am
12:30 pm
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Aurelien Lemay's Habilitation defense
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IRCICA
Thu 15th Nov
4:30 pm
5:30 pm
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Andreas Maletti in Aurélien Lemay's prehabilitation seminar
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Lille-Salle B21
Thu 15th Nov
3:30 pm
4:30 pm
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Henning Fernau in Aurélien Lemay's prehabilitation seminar:
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Lille-Salle B21
Fri 9th Nov
11:00 am
12:30 pm
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Talk of Bruno Guillon
Abstract: The time complexity of 1-limited automata is investigated from a
descriptional complexity view point. Though the model recognizes
regular languages only, it may use quadratic time in the input length.
We show that, with a polynomial increase in size and preserving
determinism, each 1-limited automaton can be transformed into a
linear-time equivalent one. We also obtain polynomial transformations
into related models, including weight-reducing Hennie machines (i.e.,
one-tape Turing machines syntactically forced to operate in
linear-time), and we show exponential gaps for converse
transformations in the deterministic case.
Fri 26th Oct
11:00 am
12:30 pm
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Momar Sakho in Links seminar
"Lieu : Lille, Salle : A12"
Thu 18th Oct
4:00 pm
5:00 pm
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Talk of Mikael Monet
Title: Combined Complexity of Probabilistic Query Evaluation

Abstract:
Query evaluation over probabilistic databases (probabilistic query evaluation, or PQE) is known to be intractable in many cases, even in data complexity, i.e., when the query is fixed. Although some restrictions of the queries and instances have been proposed to lower the complexity, these known tractable cases usually do not apply to combined complexity, i.e., when the query is not fixed. This talk gives an overview of my PhD research, which investigates which queries and instances ensure the tractability of PQE in combined complexity.

I will first present our work on PQE of conjunctive queries on binary signatures, which can be rephrased as a probabilistic graph homomorphism problem. We restrict the query and instance graphs to be trees and show the impact on the combined complexity of diverse features such as edge labels, branching, or connectedness. This is joint work with Antoine Amarilli and Pierre Senellart and was presented at PODS'2017.

Second, we will explore the combined complexity of evaluating queries on treelike databases, i.e., databases whose treewidth is bounded by a constant. We introduce a class of queries (named 'CFG-Datalog') which generalizes many known query languages that are tractable in this context. Specifically, we show that the (non-probabilistic) evaluation of CFG-Datalog on treelike databases can be solved with complexity linear in the product of the instance size and of the query size. In the process, we introduce a new representation of the provenance of a query on a database, based on cyclic Boolean circuits. This is joint work with Antoine Amarilli, Pierre Bourhis, and Pierre Senellart, and was presented at ICDT'2017.

Last, we will move to the field of knowledge compilation and present our work that connects various notions of width for Boolean circuits. We show that circuits of bounded treewidth can be efficiently compiled into structured deterministic decomposable normal forms (d-SDNNFs), which in particular allows efficient probability computation. We show the implications of this result for PQE of CFG-Datalog on treelike databases. We also prove general lower bounds on knowledge compilation formalisms, which imply lower bounds for provenance computation. This is joint work with Antoine Amarilli and Pierre Senellart and was presented at ICDT'2018.
"Lieu : Lille, Salle : B21"
Fri 28th Sep
10:15 am
11:45 am
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José Lozano Links seminar
Fri 21st Sep
10:30 am
12:00 pm
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Fabian Reiter in Links' Seminar: Descriptive distributed complexity
This talk connects two classical areas of theoretical computer science: descriptive complexity and distributed computing. The former is a branch of computational complexity theory that characterizes complexity classes in terms of equivalent logical formalisms. The latter studies algorithms that run in networks of interconnected processors.

Although an active field of research since the late 1970s, distributed computing is still lacking the analogue of a complexity theory. One reason for this may be the large number of distinct models of distributed computation, which make it rather difficult to develop a unified formal framework. In my talk, I will outline how the descriptive approach, i.e., connections to logic, could be helpful in this regard.
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Salle B21
Fri 7th Sep
11:00 am
12:30 pm
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Rustam Azimov in Links Seminar: "Context-Free Path Querying by Matrix Multiplication"

Permanent link to this article: https://team.inria.fr/links/seminars/