Cristian Versari

dblp:06/1419 · DBLP profile ↗
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10ranked-venue papers
4as first author
2since 2021 · last 2022
—ORCID · none

Domains — the database's venue-derived domains; a paper can count in several

Theory of computation · 6 · 3 first-author · 1 since 2021Software engineering, systems software and programming languages · 3 · 1 first-authorGraphics, computer vision, multimedia, augmented reality and games · 1 · 1 since 2021Applied, interdisciplinary, general and emerging computing · 1
YearPublicationVenuePosition
2022 SODA: Self-Organizing Data Augmentation in Deep Neural Networks Application to Biomedical Image Segmentation Tasks
abstract
In practice, data augmentation is assigned a predefined budget in terms of newly created samples per epoch. When using several types of data augmentation, the budget is usually uniformly distributed over the set of augmentations but one can wonder if this budget should not be allocated to each type in a more efficient way. This paper leverages online learning to allocate on the fly this budget as part of neural network training. This meta-algorithm can be run at almost no extra cost as it exploits gradient based signals to determine which type of data augmentation should be preferred. Experiments suggest that this strategy can save computation time and thus goes in the way of greener machine learning practices.
Arnaud Deleruyelle, John Klein, Cristian Versari
ICASSP3
2021 Computing difference abstractions of linear equation systems
Emilie Allart, Joachim Niehren, Cristian Versari
Theor. Comput. Sci.3
2016 What Population Reveals about Individual Cell Identity: Single-Cell Parameter Estimation of Models of Gene Expression in Yeast
abstract
Significant cell-to-cell heterogeneity is ubiquitously observed in isogenic cell populations. Consequently, parameters of models of intracellular processes, usually fitted to population-averaged data, should rather be fitted to individual cells to obtain a population of models of similar but non-identical individuals. Here, we propose a quantitative modeling framework that attributes specific parameter values to single cells for a standard model of gene expression. We combine high quality single-cell measurements of the response of yeast cells to repeated hyperosmotic shocks and state-of-the-art statistical inference approaches for mixed-effects models to infer multidimensional parameter distributions describing the population, and then derive specific parameters for individual cells. The analysis of single-cell parameters shows that single-cell identity (e.g. gene expression dynamics, cell size, growth rate, mother-daughter relationships) is, at least partially, captured by the parameter values of gene expression models (e.g. rates of transcription, translation and degradation). Our approach shows how to use the rich information contained into longitudinal single-cell data to infer parameters that can faithfully represent single-cell identity.
Artémis Llamosi, Andrés M. González-Vargas, Cristian Versari, Eugenio Cinquemani, Giancarlo Ferrari-Trecate, Pascal Hersen, Grégory Batt
PLoS Comput. Biol.3
2011 Biochemical Reaction Rules with Constraints
Mathias John, Cédric Lhoussaine, Joachim Niehren, Cristian Versari
ESOP4
2011 An Operational Petri Net Semantics for A2CCS
abstract
A 2 CCS is a conservative extension of CCS, enriched with an operator of strong prefixing, enabling the modeling of atomic sequences and multi-party synchronization (realized as an atomic sequence of binary synchronizations); the classic dining philosophers problem is used to illustrate the approach. A step semantics for A 2 CCS is also presented directly as a labeled transition system. A safe Petri net semantics for this language is presented, following the approach of Degano, De Nicola, Montanari and Olderog. We prove that a process p and its associated net Net(p) are interleaving bisimilar (Theorem 5.1). Moreover, to support the claim that the intended concurrency is well-represented in the net, we also prove that a process p and its associated net Net(p) are step bisimilar (Theorem 5.2).
Roberto Gorrieri, Cristian Versari
Fundam. Informaticae2
2009 On the Expressive Power of Restriction and Priorities in CCS with Replication
Jesús Aranda, Frank D. Valencia, Cristian Versari
FoSSaCS3
2009 An expressiveness study of priority in process calculi
abstract
Priority is a frequently used feature of many computational systems. In this paper we study the expressiveness of two process algebras enriched with different priority mechanisms. In particular, we consider a finite (that is, recursion-free) fragment of asynchronous CCS with global priority (FAP, for short) and Phillips' CPG (CCS with local priority), and contrast their expressive power with that of two non-prioritised calculi, namely the π-calculus and its broadcast-based version, called bπ. We prove, by means of leader-election-based separation results, that, under certain conditions, there exists no encoding of FAP in π-Calculus or CPG. Moreover, we single out another problem in distributed computing, which we call thelast man standingproblem (LMS for short), that better reveals the gap between the two prioritised calculi above and the two non-prioritised ones, by proving that there exists no parallel-preserving encoding of the prioritised calculi in the non-prioritised calculi retaining anysincere(complete but partially correct, that is, admitting divergence or premature termination) semantics.
Cristian Versari, Nadia Busi, Roberto Gorrieri
Math. Struct. Comput. Sci.1
2009 Stochastic biological modelling in the presence of multiple compartments
Cristian Versari, Nadia Busi
Theor. Comput. Sci.1
2007 On the Expressive Power of Global and Local Priority in Process Calculi
Cristian Versari, Nadia Busi, Roberto Gorrieri
CONCUR1
2007 A Core Calculus for a Comparative Analysis of Bio-inspired Calculi
Cristian Versari
ESOP1