Seminars

Links' Seminars and Public Events Add to google calendar
2024
Fri 7th Jun
10:00 am
11:00 am
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Séminaire Sam Van Gool dualité de Stone

Thu 30th May
to Fri 31st May
 all day
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Pysemigroup Hackaton

Fri 24th May
11:00 am
11:30 am
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Séminaire Sophie Tison
Speaker: Sophie Tison

Title: Containment of Regular Path Queries Under Constraints
Thu 16th May
2:00 pm
4:00 pm
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Seminar Arkaprava
Title: Efficient Optimization of Network Metrics in Large Uncertain
Graphs

Abstract: Graphs constitute an omnipresent data structure that can
model objects and their relationships in a wide variety of real-world
scenarios. The optimization of network metrics finds use in a plethora
of real-world applications. Most of the exact techniques for such tasks
turn out to be prohibitively time-consuming and memory-intensive for
the huge graphs that are usually encountered. Thus, there is a need for
efficient approximation algorithms. This talk focuses on the efficient
optimization of network metrics in large uncertain graphs, and
specifically the following three research problems. The first problem
aims to find, between a given pair of nodes in an uncertain graph, the
path having the highest probability of being a shortest path. The
second problem aims to find, in an uncertain graph, the subgraph having
the highest probability of being densest. The third problem is a novel
variant of the well-known opinion maximization problem where, given a
social network of users with real-valued opinions (about different
candidates), the goal is to choose the top-k seed users maximizing a
specific voting-based score at a given finite time horizon.
Best Regards,
Arkaprava
"Lieu : Lille, Salle : B11"
Fri 19th Apr
11:00 am
12:00 pm
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Seminar Pierre Lermusiaux
Speaker: Pierre Lermusiaux (plermusi.github.io/)

Title: Detection of Uncaught Exceptions in Functional Programs by Abstract
Interpretation

Abstract:

Exception handling is a key feature in modern programming languages. Exceptions
can be used to deal with errors, or as a means to control the flow of execution
of a program. Since they might unexpectedly terminate a program, unhandled
exceptions are a serious safety concern. We propose a static analysis to detect
uncaught exceptions in functional programs, that is defined as an abstract
interpreter. It computes a description of the values potentially returned by a
program using a novel abstract domain, that can express inductively defined
sets of values. Simultaneously, the analysis infers the possibly raised
exceptions, by computing in the abstract exception monad. This abstract
interpreter has been implemented as an effective static analyser for a large
subset of OCaml programs, that supports mutable data types, the OCaml module
system, and dynamically extensible data types such as the exception type. The
analyser has been evaluated on several hundreds of OCaml programs.
Fri 5th Apr
10:30 am
11:30 am
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Séminaire Guillaume Lagarde
Titre: Scaling Neural Program Synthesis with Distribution-based Search
Abstract:
In this talk, we will discuss the problem of automatically constructing
computer programs from input-output examples, especially when the
target language is domain-specific and defined using a context-free
grammar. I will introduce a theoretical framework called
distribution-based search, discuss its challenges, and present several
search strategies based on learning the weights of a probabilistic
context-free grammar (PCFG) and then using this PCFG to enumerate the
most promising candidate programs efficiently.
The presentation will be based on the following paper published at
AAAI'2022: arxiv.org/abs/2110.12485
Joint work with Nathanaël Fijalkow, Théo Matricon, Kevin Ellis, Pierre
Ohlmann, Akarsh Potta

Fri 2nd Feb
10:30 am
11:30 am
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Mikaël Monet: Probabiliste Shapley value

Fri 26th Jan
10:00 am
11:00 am
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Séminaire: Klara Nosan
Sujet: TBA

2023
Thu 14th Dec
2:00 pm
5:00 pm
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Claire Soyez-Martin PhD defense
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Amphi IRCICA
Fri 1st Dec
10:00 am
11:00 am
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Séminaire Oliver
Titre: Direct Access for Conjunctive Queries with Negation
Abstract:
Direct Access is the operation of returning, given an index j, the jth answer of a conjunctive query on a given database for a given order. While this problem is #P-hard in general (wrt combined complexity), many conjunctive queries are structured enough so that for some lexicographical ordering of their answers, one can have a direct access to the answer set of a query Q that takes polylogarithmic time in the size of the database after a polynomial time precomputation. Previous work has precisely characterised the tractable classes and given fined-grained lower bounds on the time needed for precomputation depending on the structure of the query. We give a generalisation of these tractability results to the case of signed conjunctive queries, that is, conjunctive queries that may contain negative atoms. Our technique is based on solving the direct access task for a class of circuits that can represent relational data. Our result then follows from the fact that the tractable (signed) conjunctive queries can be transformed into polynomial size circuits. We recover the known tractable classes from the literature in the case of positive conjunctive queries using this technique and also discover new islands of tractability for signed conjunctive queries. In particular, our result generalises to the Direct Access Problem the known tractabilities of counting the number of answers to beta-acyclic negative queries and of deciding whether a negative query with bounded nested-width has an answer. This is joint work with Florent Capelli.
Fri 24th Nov
10:00 am
11:00 am
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Séminaire Pierre Vandenhove

Fri 17th Nov
10:00 am
11:00 am
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Séminaire Charles (RsonPath)
TBA
Fri 10th Nov
10:00 am
11:00 am
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Séminaire Nils Vortmeier
title: TBA
Fri 20th Oct
10:30 am
12:30 pm
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Aurelien part II

Fri 22nd Sep
11:00 am
12:00 pm
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Séminaire Théo Losekoot
Title: Automata-based verification of relational properties of functions over algebraic data structures
Fri 15th Sep
11:00 am
12:30 pm
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Charles: Présentation de rsonpath

Fri 23rd Jun
11:00 am
12:00 pm
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Seminar by Florent Capelli
Speaker: Florent Capelli — florent.capelli.me/

Title: A simpler FPRAS for nOBDD

Abstract: A simpler FPRAS for nOBDD

Abstract: In this talk, we revisit the algorithm by Arenas, Croquevielle, Jayaram and Riveros that allows to approximate the number of words of length n of a non deterministic finite automaton. We explain the algorithm and techniques in a modular and general way, without relating to the particular case of counting words in automaton. We illustrate the soundness of the approach by applying it to the problem of approximatively counting the number of satisfying assignments of a non-deterministic OBDD.
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B21
Fri 2nd Jun
11:00 am
12:30 pm
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Séminaire Martin Berger
Title: Search-Based Regular Expression Inference on a GPU

Abstract: Regular expression inference (REI) is a supervised machine
learning and program synthesis problem that takes a cost metric for regular
expressions, and positive and negative examples of strings as input. It
outputs a regular expression that is precise (i.e., accepts all positive
and rejects all negative examples), and minimal w.r.t. to the cost metric.
We present a novel algorithm for REI over arbitrary alphabets that is
enumerative and trades off time for space. Our main algorithmic idea is to
implement the search space of regular expressions succinctly as a
contiguous matrix of bitvectors. Collectively, the bitvectors represent, as
characteristic sequences, all sub-languages of the infix-closure of the
union of positive and negative examples. Mathematically, this is a semiring
of (a variant of) formal power series. Infix-closure enables bottom-up
compositional construction of larger from smaller regular expressions using
the operations of our semiring. This minimises data movement and
data-dependent branching, hence maximises data-parallelism. In addition,
the infix-closure remains unchanged during the search, hence search can be
staged: first pre-compute various expensive operations, and then run the
compute intensive search process. We provide two C++ implementations, one
for general purpose CPUs and one for Nvidia GPUs (using CUDA). We benchmark
both on Google Colab Pro: the GPU implementation is on average over 1000x
faster than the CPU implementation on the hardest benchmarks.

Joint work with Mojtaba Valizadeh

Download: martinfriedrichberger.net/pldi2023.html

Thu 13th Apr
11:00 am
12:00 pm
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Séminaire Yann Strozecki

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Esprit salle Agora 2 (rez-de-chaussée)
Tue 11th Apr
2:00 pm
3:00 pm
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Séminaire Mamadou

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Esprit Agora 1 (rez-de-chaussée)
Fri 24th Mar
10:00 am
11:00 am
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Séminaire Mamadou KANTE

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Lien Permanent pour cet article : https://team.inria.fr/links/fr/seminars/