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	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
	Volume	11	Issue	1	Pages	13-25
	Keywords
	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.
	Address
	Corporate Author				Thesis
	Publisher	Springer-Verlag	Place of Publication	Berlin, Heidelberg	Editor
	Language		Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	1433-2779	ISBN		Medium
	Area		Expedition		Conference
	Notes				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
	Volume	86	Issue	3	Pages	232-244
	Keywords
	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.
	Address
	Corporate Author				Thesis
	Publisher	Elsevier North-Holland, Inc.	Place of Publication	New York, NY, USA	Editor
	Language		Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	0169-2607	ISBN		Medium
	Area		Expedition		Conference
	Notes				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
	Volume		Issue		Pages	4
	Keywords
	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.
	Address
	Corporate Author				Thesis
	Publisher	IEEE Computer Society	Place of Publication		Editor
	Language		Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	0-7695-2859-5	ISBN		Medium
	Area		Expedition		Conference
	Notes				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
	Volume	6	Issue	4	Pages	320-341
	Keywords
	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$\varphi$.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language		Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN		ISBN		Medium
	Area		Expedition		Conference
	Notes				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
	Volume		Issue		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.
	Address
	Corporate Author				Thesis
	Publisher	IEEE Press	Place of Publication	Piscataway, NJ, USA	Editor	Cimatti, A.; Jones, R.
	Language		Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	978-1-4244-2735-2	ISBN		Medium
	Area		Expedition		Conference
	Notes				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
	Volume		Issue		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.
	Address
	Corporate Author				Thesis
	Publisher	Acm	Place of Publication		Editor	Najork, M.; Broder, A.Z.; Chakrabarti, S.
	Language		Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN		ISBN		Medium
	Area		Expedition		Conference
	Notes				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	Abbreviated Journal
	Volume		Issue		Pages	6120-6125
	Keywords
	Abstract
	Address
	Corporate Author				Thesis
	Publisher	IEEE	Place of Publication		Editor
	Language		Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN		ISBN	978-1-4673-2065-8	Medium
	Area		Expedition		Conference
	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	Abbreviated Journal
	Volume		Issue		Pages	227-236
	Keywords
	Abstract
	Address
	Corporate Author				Thesis
	Publisher	ACM	Place of Publication		Editor	Ahmed Jerraya and Luca P. Carloni and Florence Maraninchi and John Regehr
	Language		Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN		ISBN	978-1-4503-1425-1	Medium
	Area		Expedition		Conference
	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	Abbreviated Journal
	Volume		Issue		Pages	664-671
	Keywords
	Abstract
	Address
	Corporate Author				Thesis
	Publisher	ThinkMind	Place of Publication		Editor
	Language		Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN		ISBN		Medium
	Area		Expedition		Conference
	Notes				Approved	yes
	Call Number	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	Abbreviated Journal
	Volume		Issue		Pages	15-20
	Keywords
	Abstract
	Address
	Corporate Author				Thesis
	Publisher	ThinkMind	Place of Publication		Editor
	Language		Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	978-1-61208-226-4	ISBN		Medium
	Area		Expedition		Conference
	Notes				Approved	yes
	Call Number	Sapienza @ mari @ infocomp2012			Serial	100
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