| Records |
| Author |
Melatti, Igor; Palmer, Robert; Sawaya, Geoffrey; Yang, Yu; Kirby, Robert Mike; Gopalakrishnan, Ganesh |
| Title |
Parallel and distributed model checking in Eddy |
Type |
Journal Article |
| Year |
2009 |
Publication |
Int. J. Softw. Tools Technol. Transf. |
Abbreviated Journal |
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| Volume |
11 |
Issue |
1 |
Pages |
13-25 |
| Keywords |
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| Abstract |
Model checking of safety properties can be scaled up by pooling the CPU and memory resources of multiple computers. As compute clusters containing 100s of nodes, with each node realized using multi-core (e.g., 2) CPUs will be widespread, a model checker based on the parallel (shared memory) and distributed (message passing) paradigms will more efficiently use the hardware resources. Such a model checker can be designed by having each node employ two shared memory threads that run on the (typically) two CPUs of a node, with one thread responsible for state generation, and the other for efficient communication, including (1) performing overlapped asynchronous message passing, and (2) aggregating the states to be sent into larger chunks in order to improve communication network utilization. We present the design details of such a novel model checking architecture called Eddy. We describe the design rationale, details of how the threads interact and yield control, exchange messages, as well as detect termination. We have realized an instance of this architecture for the Murphi modeling language. Called Eddy_Murphi, we report its performance over the number of nodes as well as communication parameters such as those controlling state aggregation. Nearly linear reduction of compute time with increasing number of nodes is observed. Our thread task partition is done in such a way that it is modular, easy to port across different modeling languages, and easy to tune across a variety of platforms. |
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| Publisher |
Springer-Verlag |
Place of Publication |
Berlin, Heidelberg |
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Edition |
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| ISSN |
1433-2779 |
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Approved |
yes |
| Call Number |
Sapienza @ mari @ Mpsykg09 |
Serial |
80 |
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| Author |
Intrigila, Benedetto; Melatti, Igor; Tofani, Alberto; Macchiarelli, Guido |
| Title |
Computational models of myocardial endomysial collagen arrangement |
Type |
Journal Article |
| Year |
2007 |
Publication |
Computer Methods and Programs in Biomedicine |
Abbreviated Journal |
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| Volume |
86 |
Issue |
3 |
Pages |
232-244 |
| Keywords |
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| Abstract |
Collagen extracellular matrix is one of the factors related to high passive stiffness of cardiac muscle. However, the architecture and the mechanical aspects of the cardiac collagen matrix are not completely known. In particular, endomysial collagen contribution to the passive mechanics of cardiac muscle as well as its micro anatomical arrangement is still a matter of debate. In order to investigate mechanical and structural properties of endomysial collagen, we consider two alternative computational models of some specific aspects of the cardiac muscle. These two models represent two different views of endomysial collagen distribution: (1) the traditional view and (2) a new view suggested by the data obtained from scanning electron microscopy (SEM) in NaOH macerated samples (a method for isolating collagen from the other tissue). We model the myocardial tissue as a net of spring elements representing the cardiomyocytes together with the endomysial collagen distribution. Each element is a viscous elastic spring, characterized by an elastic and a viscous constant. We connect these springs to imitate the interconnections between collagen fibers. Then we apply to the net of springs some external forces of suitable magnitude and direction, obtaining an extension of the net itself. In our setting, the ratio forces magnitude /net extension is intended to model the stress /strain ratio of a microscopical portion of the myocardial tissue. To solve the problem of the correct identification of the values of the different parameters involved, we use an artificial neural network approach. In particular, we use this technique to learn, given a distribution of external forces, the elastic constants of the springs needed to obtain a desired extension as an equilibrium position. Our experimental findings show that, in the model of collagen distribution structured according to the new view, a given stress /strain ratio (of the net of springs, in the sense specified above) is obtained with much smaller (w.r.t. the other model, corresponding to the traditional view) elasticity constants of the springs. This seems to indicate that by an appropriate structure, a given stiffness of the myocardial tissue can be obtained with endomysial collagen fibers of much smaller size. |
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Elsevier North-Holland, Inc. |
Place of Publication |
New York, NY, USA |
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Edition |
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| ISSN |
0169-2607 |
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Approved |
yes |
| Call Number |
Sapienza @ mari @ Imtm07 |
Serial |
82 |
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| Author |
Della Penna, Giuseppe; Magazzeni, Daniele; Tofani, Alberto; Intrigila, Benedetto; Melatti, Igor; Tronci, Enrico |
| Title |
Automatic Synthesis of Robust Numerical Controllers |
Type |
Conference Article |
| Year |
2007 |
Publication |
Icas '07 |
Abbreviated Journal |
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| Volume |
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Issue |
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Pages |
4 |
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| Abstract |
A major problem of numerical controllers is their robustness, i.e. the state read from the plant may not be in the controller table, although it may be close to some states in the table. For continuous systems, this problem is typically handled by interpolation techniques. Unfortunately, when the plant contains both continuous and discrete variables, the interpolation approach does not work well. To cope with this kind of systems, we propose a general methodology that exploits explicit model checking in an innovative way to automatically synthesize a (time-) optimal numerical controller from a plant specification and apply an optimized strengthening algorithm only on the most significant states, in order to reach an acceptable robustness degree. We implemented all the algorithms within our CGMurphi tool, an extension of the well-known CMurphi verifier, and tested the effectiveness of our approach by applying it to the well-known truck and trailer obstacles avoidance problem. |
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| Publisher |
IEEE Computer Society |
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| ISSN |
0-7695-2859-5 |
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Approved |
yes |
| Call Number |
Sapienza @ mari @ Dmtimt07 |
Serial |
89 |
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| Author |
Della Penna, Giuseppe; Intrigila, Benedetto; Melatti, Igor; Tronci, Enrico; Venturini Zilli, Marisa |
| Title |
Exploiting Transition Locality in Automatic Verification of Finite State Concurrent Systems |
Type |
Journal Article |
| Year |
2004 |
Publication |
Sttt |
Abbreviated Journal |
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| Volume |
6 |
Issue |
4 |
Pages |
320-341 |
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| Abstract |
In this paper we show that statistical properties of the transition graph of a system to be verified can be exploited to improve memory or time performances of verification algorithms. We show experimentally that protocols exhibit transition locality. That is, with respect to levels of a breadth-first state space exploration, state transitions tend to be between states belonging to close levels of the transition graph. We support our claim by measuring transition locality for the set of protocols included in the Mur$\varphi$ verifier distribution. We present a cache-based verification algorithm that exploits transition locality to decrease memory usage and a disk-based verification algorithm that exploits transition locality to decrease disk read accesses, thus reducing the time overhead due to disk usage. Both algorithms have been implemented within the Mur$\varphi$ verifier. Our experimental results show that our cache-based algorithm can typically save more than 40% of memory with an average time penalty of about 50% when using (Mur$\varphi$) bit compression and 100% when using bit compression and hash compaction, whereas our disk-based verification algorithm is typically more than ten times faster than a previously proposed disk-based verification algorithm and, even when using 10% of the memory needed to complete verification, it is only between 40 and 530% (300% on average) slower than (RAM) Mur$\varphi$ with enough memory to complete the verification task at hand. Using just 300 MB of memory our disk-based Mur$\varphi$ was able to complete verification of a protocol with about $10^9$ reachable states. This would require more than 5 GB of memory using standard Mur$\varphi$. |
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Approved |
yes |
| Call Number |
Sapienza @ mari @ DIMTZ04j |
Serial |
91 |
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| Author |
Mari, Federico; Melatti, Igor; Salvo, Ivano; Tronci, Enrico; Alvisi, Lorenzo; Clement, Allen; Li, Harry |
| Title |
Model Checking Nash Equilibria in MAD Distributed Systems |
Type |
Conference Article |
| Year |
2008 |
Publication |
FMCAD '08: Proceedings of the 2008 International Conference on Formal Methods in Computer-Aided Design |
Abbreviated Journal |
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| Volume |
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Issue |
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Pages |
1-8 |
| Keywords |
Model Checking, MAD Distributed System, Nash Equilibrium |
| Abstract |
We present a symbolic model checking algorithm for verification of Nash equilibria in finite state mechanisms modeling Multiple Administrative Domains (MAD) distributed systems. Given a finite state mechanism, a proposed protocol for each agent and an indifference threshold for rewards, our model checker returns PASS if the proposed protocol is a Nash equilibrium (up to the given indifference threshold) for the given mechanism, FAIL otherwise. We implemented our model checking algorithm inside the NuSMV model checker and present experimental results showing its effectiveness for moderate size mechanisms. For example, we can handle mechanisms which corresponding normal form games would have more than $10^20$ entries. To the best of our knowledge, no model checking algorithm for verification of mechanism Nash equilibria has been previously published. |
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| Publisher |
IEEE Press |
Place of Publication |
Piscataway, NJ, USA |
Editor |
Cimatti, A.; Jones, R. |
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978-1-4244-2735-2 |
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Approved |
yes |
| Call Number |
Sapienza @ mari @ MarMelSalTroAlvCle08 |
Serial |
93 |
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| Author |
Chierichetti, Flavio; Lattanzi, Silvio; Mari, Federico; Panconesi, Alessandro |
| Title |
On Placing Skips Optimally in Expectation |
Type |
Conference Article |
| Year |
2008 |
Publication |
Web Search and Web Data Mining (WSDM 2008) |
Abbreviated Journal |
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Issue |
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Pages |
15-24 |
| Keywords |
Information Retrieval |
| Abstract |
We study the problem of optimal skip placement in an inverted list. Assuming the query distribution to be known in advance, we formally prove that an optimal skip placement can be computed quite efficiently. Our best algorithm runs in time O(n log n), n being the length of the list. The placement is optimal in the sense that it minimizes the expected time to process a query. Our theoretical results are matched by experiments with a real corpus, showing that substantial savings can be obtained with respect to the tra- ditional skip placement strategy, that of placing consecutive skips, each spanning sqrt(n) many locations. |
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Acm |
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Editor |
Najork, M.; Broder, A.Z.; Chakrabarti, S. |
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Approved |
yes |
| Call Number |
Sapienza @ mari @ ChiLatMar08 |
Serial |
94 |
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| Author |
Alimguzhin, Vadim; Mari, Federico; Melatti, Igor; Salvo, Ivano; Tronci, Enrico |
| Title |
Automatic Control Software Synthesis for Quantized Discrete Time Hybrid Systems |
Type |
Conference Article |
| Year |
2012 |
Publication |
Proceedings of the 51th IEEE Conference on Decision and Control, CDC 2012, December 10-13, 2012, Maui, HI, USA |
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Pages |
6120-6125 |
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IEEE |
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ISBN |
978-1-4673-2065-8 |
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| Notes |
Techreport version can be found at http://arxiv.org/abs/1207.4098 |
Approved |
yes |
| Call Number |
Sapienza @ mari @ cdc12 |
Serial |
96 |
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| Author |
Alimguzhin, Vadim; Mari, Federico; Melatti, Igor; Salvo, Ivano; Tronci, Enrico |
| Title |
On Model Based Synthesis of Embedded Control Software |
Type |
Conference Article |
| Year |
2012 |
Publication |
Proceedings of the 12th International Conference on Embedded Software, EMSOFT 2012, part of the Eighth Embedded Systems Week, ESWeek 2012, Tampere, Finland, October 7-12, 2012 |
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Pages |
227-236 |
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ACM |
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Editor |
Ahmed Jerraya and Luca P. Carloni and Florence Maraninchi and John Regehr |
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978-1-4503-1425-1 |
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| Notes |
Techreport version can be found at arxiv.org |
Approved |
yes |
| Call Number |
Sapienza @ mari @ emsoft12 |
Serial |
97 |
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| Author |
Mari, Federico; Melatti, Igor; Salvo, Ivano; Tronci, Enrico |
| Title |
Linear Constraints as a Modeling Language for Discrete Time Hybrid Systems |
Type |
Conference Article |
| Year |
2012 |
Publication |
Proceedings of ICSEA 2012, The Seventh International Conference on Software Engineering Advances |
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Issue |
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Pages |
664-671 |
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ThinkMind |
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Approved |
yes |
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Sapienza @ mari @ icsea12 |
Serial |
98 |
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| Author |
Mari, Federico; Melatti, Igor; Salvo, Ivano; Tronci, Enrico |
| Title |
Control Software Visualization |
Type |
Conference Article |
| Year |
2012 |
Publication |
Proceedings of INFOCOMP 2012, The Second International Conference on Advanced Communications and Computation |
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Issue |
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Pages |
15-20 |
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ThinkMind |
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978-1-61208-226-4 |
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Approved |
yes |
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Sapienza @ mari @ infocomp2012 |
Serial |
100 |
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