Jeanneret C.,University of Zürich |
Glinz M.,University of Zürich |
Proceedings - International Conference on Software Engineering | Year: 2011
When performed on a model, a set of operations (e.g., queries or model transformations) rarely uses all the information present in the model. Unintended underuse of a model can indicate various problems: the model may contain more detail than necessary or the operations may be immature or erroneous. Analyzing the footprints of the operations - i.e., the part of a model actually used by an operation - is a simple technique to diagnose and analyze such problems. However, precisely calculating the footprint of an operation is expensive, because it requires analyzing the operation's execution trace. In this paper, we present an automated technique to estimate the footprint of an operation without executing it. We evaluate our approach by applying it to 75 models and five operations. Our technique provides software engineers with an efficient, yet precise, evaluation of the usage of their models. © 2011 ACM.
Tonneau S.,IRISA |
Pettre J.,French Institute for Research in Computer Science and Automation |
Multon F.,University of Rennes 2 – Upper Brittany
Proceedings - Graphics Interface | Year: 2014
A common issue in three-dimensional animation is the creation of contacts between a virtual creature and the environment. Contacts allow force exertion, which produces motion. This paper addresses the problem of computing contact configurations allowing to perform motion tasks such as getting up from a sofa, pushing an object or climbing. We propose a two-step method to generate contact configurations suitable for such tasks. The first step is an offline sampling of the reachable workspace of a virtual creature. The second step is a run time request confronting the samples with the current environment. The best contact configurations are then selected according to a heuristic for task efficiency. The heuristic is inspired by the force transmission ratio. Given a contact configuration, it measures the potential force that can be exerted in a given direction. Our method is automatic and does not require examples or motion capture data. It is suitable for real time applications and applies to arbitrary creatures in arbitrary environments. Various scenarios (such as climbing, crawling, getting up, pushing or pulling objects) are used to demonstrate that our method enhances motion autonomy and interactivity in constrained environments. Copyright held by authors.
Crain T.,IRISA |
Gramoli V.,Ecole Polytechnique Federale de Lausanne |
Raynal M.,Institut Universitaire de France
Proceedings of the ACM SIGPLAN Symposium on Principles and Practice of Parallel Programming, PPOPP | Year: 2012
We introduce the first binary search tree algorithm designed for speculative executions. Prior to this work, tree structures were mainly designed for their pessimistic (non-speculative) accesses to have a bounded complexity. Researchers tried to evaluate transactional memory using such tree structures whose prominent example is the red-black tree library developed by Oracle Labs that is part of multiple benchmark distributions. Although well-engineered, such structures remain badly suited for speculative accesses, whose step complexity might raise dramatically with contention. We show that our speculation-friendly tree outperforms the existing transaction-based version of the AVL and the red-black trees. Its key novelty stems from the decoupling of update operations: they are split into one transaction that modifies the abstraction state and multiple ones that restructure its tree implementation in the background. In particular, the speculation-friendly tree is shown correct, reusable and it speeds up a transaction-based travel reservation application by up to 3.5×. Copyright © 2012 ACM.
Imbs D.,IRISA |
Proceedings of the Annual ACM Symposium on Principles of Distributed Computing | Year: 2010
The Borowsky-Gafni (BG) simulation algorithm is a powerful reduction algorithm that shows that t-resilience of decision tasks can be fully characterized in terms of wait-freedom. Said in another way, the BG simulation shows that the crucial parameter is not the number n of processes but the upper bound t on the number of processes that are allowed to crash. The BG algorithm considers colorless decision tasks in the base read/write shared memory model. (Colorless means that if, a process decides a value, any other process is allowed to decide the very same value.) This paper considers system models made up of n processes prone to up to t crashes, and where the processes communicate by accessing read/write atomic registers (as assumed by the BG) and (differently from the BG) objects with consensus number x, accessible by at most x processes (with x ≤ t < n). Let ASM(n, t, x) denote such a system model. While the BG simulation has shown that the models ASM(n, t, 1) and ASM(t + 1, t, 1) are equivalent, this paper focuses the pair (t, x) of parameters of a system model. Its main result is the following: the system models ASM(n1, t 1, x1) and ASM(n2, t2, x 2) have the same computational power for colorless decision tasks if and only if ⌊ t1/x1 ⌋ = ⌊ t 2/x2 ⌋. As can be seen, this contribution complements and extends the BG simulation. It shows that consensus numbers have a multiplicative power with respect to failures, namely the system models ASM(n, t′, x) and ASM(n, t, 1) are equivalent for colorless decision tasks iff (t × x) ≤ t′ ≤ (t × x) + (x - 1). Copyright 2010 ACM.
European Control Conference, ECC 1999 - Conference Proceedings | Year: 2015
We review several existing detectability and isolability definitions. We argue that two types of de nitions have to be distinguished. On one hand, intrinsic de nitions capture the signature of the fault on the system. On the other hand, performance-based de nitions involve indexes of performance of fault detection algorithms. In particular, since many fault detection algorithms involve a residual generation mechanism, such de nitions may capture, among other performance indexes, the signature of the fault on the residuals. In the particular case of sensor and actuator faults in linear dynamic systems, we exhibit an equivalence among several de nitions. © 1999 EUCA.
Perais A.,IRISA |
Proceedings - International Symposium on High-Performance Computer Architecture | Year: 2016
Sharing a physical register between several instructions is needed to implement several microarchitectural optimizations. However, register sharing requires modifications to the register reclaiming process: Committing a single instruction does not guarantee that the physical register allocated to the previous mapping of its architectural destination register is free-able anymore. Consequently, a form of register reference counting must be implemented. While such mechanisms (e.g., dependency matrix, per register counters) have been described in the literature, we argue that they either require too much storage, or that they lengthen branch misprediction recovery by requiring sequential rollback. As an alternative, we present the Inflight Shared Register Buffer (ISRB), a new structure for register reference counting. The ISRB has low storage overhead and lends itself to checkpoint-based recovery schemes, therefore allowing fast recovery on pipeline flushes. We illustrate our scheme with Move Elimination (short-circuiting moves) and an implementation of Speculative Memory Bypassing (short-circuiting store-load pairs) that makes use of a TAGE-like predictor to identify memory dependencies. We show that the whole potential of these two mechanisms can be achieved with a small register tracking structure. © 2016 IEEE.
Signal Processing | Year: 2013
This paper provides an annotated bibliography for investigations based on or related to divergence measures for statistical data processing and inference problems. © 2012 Elsevier B.V. All rights reserved.
Delaye A.,IRISA |
Pattern Recognition | Year: 2013
As the rise of pen-enabled interfaces is accompanied with an increased number of techniques for recognition of pen-based input, recent trends in symbol recognition show an escalation in systems complexity (number of features, classifiers combination) or the over-specialization of systems to specific datasets or applications. Despite the importance of representation space in feature-based methods, few works focus on the design of feature sets adapted to a large variety of symbols, and no universal representation space was proposed as a benchmarking reference. We introduce in this work HBF49, a unique set of features for the representation of hand-drawn symbols to be used as a reference for evaluation of symbol recognition systems. An empirical constructive approach is adopted for designing this set of 49 simple features, able to handle a large diversity of symbols in various experimental contexts. An original effort is made for guaranteeing transparency of features design and reproducibility of experiments. We demonstrate that using off-the-shelf statistical classifiers, the HBF49 representation performs comparably or better than state-of-the-art results reported on eight databases of hand-drawn objects. We also obtain a good recognition performance for user-defined gestures that further attests the ability of HBF49 to deal with a great variety of symbols. © 2012 Elsevier Ltd All rights reserved.
Imbs D.,IRISA |
Raynal M.,IRISA |
Taubenfeld G.,The Interdisciplinary Center
Proceedings of the Annual ACM Symposium on Principles of Distributed Computing | Year: 2010
Wait-freedom and obstruction-freedom have received a lot of attention in the literature. These are symmetric progress conditions in the sense that they consider all processes as being "equal". Wait-freedom has allowed to rank the synchronization power of objects in presence of process failures, while (the weaker) obstruction-freedom allows for simpler and more efficient object implementations. This paper introduces the notion of asymmetric progress conditions. Given an object O in a shared memory system of n processes, we say that O satisfies (y, x)-liveness if O can be accessed by a subset of y ≤ n processes only, and it guarantees wait-freedom for x processes and obstruction-freedom for the remaining y-x processes. Notice that, (n, n)-liveness is wait-freedom while (n, 0)-liveness is obstruction-freedom. The main contributions are: (1) an impossibility result showing that there is no (n, 1)-live consensus object even if one can use underlying (n- 1, n-1)-live consensus objects and registers, (2) an (n, x)-liveness hierarchy for 0 ≤ x ≤ n, and (3) an impossibility result showing that there is no consensus object for n processes that is obstruction-free with respect to all processes and fault-free with respect to a single process even if one can use underlying (n - 1, n - 1)-live consensus objects and registers (a process is fault-free if it always terminates when all the processes participate and there are no faults). (4) An implementation based on (x, x)-live objects that constructs a consensus object for any number of n ≥ x processes which satisfies an asymmetric group-based progress condition. Copyright 2010 ACM.
Petit A.,French Institute for Research in Computer Science and Automation |
Marchand E.,IRISA |
2013 IEEE International Symposium on Mixed and Augmented Reality, ISMAR 2013 | Year: 2013
This paper presents a method to address the issue of augmenting a markerless 3D object with a complex shape. It relies on a model-based tracker which takes advantage of GPU acceleration and 3D rendering in order to handle the complete 3D model, whose sharp edges are efficiently extracted. In the pose estimation step, we propose to robustly combine geometrical and color edge-based features in the nonlinear minimization process, and to integrate multiple-hypotheses in the geometrical edge-based registration phase. Our tracking method shows promising results for augmented reality applications, with a Kinect-based reconstructed 3D model. © 2013 IEEE.