| Records |
| Author |
Mari, Federico; Tronci, Enrico |
| Title |
CEGAR Based Bounded Model Checking of Discrete Time Hybrid Systems |
Type |
Conference Article |
| Year |
2007 |
Publication |
Hybrid Systems: Computation and Control (HSCC 2007) |
Abbreviated Journal |
|
| Volume |
|
Issue  |
|
Pages |
399-412 |
| Keywords |
Model Checking, Abstraction, CEGAR, SAT, Hybrid Systems, DTHS |
| Abstract |
Many hybrid systems can be conveniently modeled as Piecewise Affine Discrete Time Hybrid Systems PA-DTHS. As well known Bounded Model Checking (BMC) for such systems comes down to solve a Mixed Integer Linear Programming (MILP) feasibility problem. We present a SAT based BMC algorithm for automatic verification of PA-DTHSs. Using Counterexample Guided Abstraction Refinement (CEGAR) our algorithm gradually transforms a PA-DTHS verification problem into larger and larger SAT problems. Our experimental results show that our approach can handle PA-DTHSs that are more then 50 times larger than those that can be handled using a MILP solver. |
| Address |
|
| Corporate Author |
|
Thesis |
|
| Publisher |
Springer |
Place of Publication |
|
Editor |
Bemporad, A.; Bicchi, A.; Buttazzo, G.C. |
| Language |
|
Summary Language |
|
Original Title |
|
| Series Editor |
|
Series Title |
Lecture Notes in Computer Science |
Abbreviated Series Title |
|
| Series Volume |
4416 |
Series Issue |
|
Edition |
|
| ISSN |
|
ISBN |
|
Medium |
|
| Area |
|
Expedition |
|
Conference |
|
| Notes |
|
Approved |
yes |
| Call Number |
Sapienza @ mari @ MarTro07 |
Serial |
92 |
| Permanent link to this record |
| |
|
| |
| 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 |
| Permanent link to this record |
| |
|
| |
| Author |
Della Penna, Giuseppe; Intrigila, Benedetto; Melatti, Igor; Tronci, Enrico; Venturini Zilli, Marisa |
| Title |
Finite Horizon Analysis of Stochastic Systems with the Mur$\varphi$ Verifier |
Type |
Conference Article |
| Year |
2003 |
Publication |
Theoretical Computer Science, 8th Italian Conference, ICTCS 2003, Bertinoro, Italy, October 13-15, 2003, Proceedings |
Abbreviated Journal |
|
| Volume |
|
Issue |
|
Pages |
58-71 |
| Keywords |
|
| Abstract |
Many reactive systems are actually Stochastic Processes. Automatic analysis of such systems is usually very difficult thus typically one simplifies the analysis task by using simulation or by working on a simplified model (e.g. a Markov Chain). We present a Finite Horizon Probabilistic Model Checking approach which essentially can handle the same class of stochastic processes of a typical simulator. This yields easy modeling of the system to be analyzed together with formal verification capabilities. Our approach is based on a suitable disk based extension of the Mur$\varphi$ verifier. Moreover we present experimental results showing effectiveness of our approach. |
| Address |
|
| Corporate Author |
|
Thesis |
|
| Publisher |
Springer |
Place of Publication |
|
Editor |
Blundo, C.; Laneve, C. |
| Language |
|
Summary Language |
|
Original Title |
|
| Series Editor |
|
Series Title |
Lecture Notes in Computer Science |
Abbreviated Series Title |
|
| Series Volume |
2841 |
Series Issue |
|
Edition |
|
| ISSN |
3-540-20216-1 |
ISBN |
|
Medium |
|
| Area |
|
Expedition |
|
Conference |
|
| Notes |
|
Approved |
yes |
| Call Number |
Sapienza @ mari @ DIMTZ03c |
Serial |
90 |
| Permanent link to this record |
| |
|
| |
| Author |
Della Penna, Giuseppe; Intrigila, Benedetto; Melatti, Igor; Minichino, Michele; Ciancamerla, Ester; Parisse, Andrea; Tronci, Enrico; Venturini Zilli, Marisa |
| Title |
Automatic Verification of a Turbogas Control System with the Mur$\varphi$ Verifier |
Type |
Conference Article |
| Year |
2003 |
Publication |
Hybrid Systems: Computation and Control, 6th International Workshop, HSCC 2003 Prague, Czech Republic, April 3-5, 2003, Proceedings |
Abbreviated Journal |
|
| Volume |
|
Issue |
|
Pages |
141-155 |
| Keywords |
|
| Abstract |
Automatic analysis of Hybrid Systems poses formidable challenges both from a modeling as well as from a verification point of view. We present a case study on automatic verification of a Turbogas Control System (TCS) using an extended version of the Mur$\varphi$ verifier. TCS is the heart of ICARO, a 2MW Co-generative Electric Power Plant. For large hybrid systems, as TCS is, the modeling effort accounts for a significant part of the whole verification activity. In order to ease our modeling effort we extended the Mur$\varphi$ verifier by importing the C language long double type (finite precision real numbers) into it. We give experimental results on running our extended Mur$\varphi$ on our TCS model. For example using Mur$\varphi$ we were able to compute an admissible range of values for the variation speed of the user demand of electric power to the turbogas. |
| Address |
|
| Corporate Author |
|
Thesis |
|
| Publisher |
Springer |
Place of Publication |
|
Editor |
Maler, O.; Pnueli, A. |
| Language |
|
Summary Language |
|
Original Title |
|
| Series Editor |
|
Series Title |
Lecture Notes in Computer Science |
Abbreviated Series Title |
|
| Series Volume |
2623 |
Series Issue |
|
Edition |
|
| ISSN |
3-540-00913-2 |
ISBN |
|
Medium |
|
| Area |
|
Expedition |
|
Conference |
|
| Notes |
|
Approved |
yes |
| Call Number |
Sapienza @ mari @ Dimmcptz03 |
Serial |
88 |
| Permanent link to this record |
| |
|
| |
| Author |
Della Penna, Giuseppe; Intrigila, Benedetto; Melatti, Igor; Tronci, Enrico; Venturini Zilli, Marisa |
| Title |
Bounded Probabilistic Model Checking with the Mur$\varphi$ Verifier |
Type |
Conference Article |
| Year |
2004 |
Publication |
Formal Methods in Computer-Aided Design, 5th International Conference, FMCAD 2004, Austin, Texas, USA, November 15-17, 2004, Proceedings |
Abbreviated Journal |
|
| Volume |
|
Issue |
|
Pages |
214-229 |
| Keywords |
|
| Abstract |
In this paper we present an explicit verification algorithm for Probabilistic Systems defining discrete time/finite state Markov Chains. We restrict ourselves to verification of Bounded PCTL formulas (BPCTL), that is, PCTL formulas in which all Until operators are bounded, possibly with different bounds. This means that we consider only paths (system runs) of bounded length. Given a Markov Chain $\cal M$ and a BPCTL formula Φ, our algorithm checks if Φ is satisfied in $\cal M$. This allows to verify important properties, such as reliability in Discrete Time Hybrid Systems. We present an implementation of our algorithm within a suitable extension of the Mur$\varphi$ verifier. We call FHP-Mur$\varphi$ (Finite Horizon Probabilistic Mur$\varphi$) such extension of the Mur$\varphi$ verifier. We give experimental results comparing FHP-Mur$\varphi$ with (a finite horizon subset of) PRISM, a state-of-the-art symbolic model checker for Markov Chains. Our experimental results show that FHP-Mur$\varphi$ can effectively handle verification of BPCTL formulas for systems that are out of reach for PRISM, namely those involving arithmetic operations on the state variables (e.g. hybrid systems). |
| Address |
|
| Corporate Author |
|
Thesis |
|
| Publisher |
Springer |
Place of Publication |
|
Editor |
Hu, A.J.; Martin, A.K. |
| Language |
|
Summary Language |
|
Original Title |
|
| Series Editor |
|
Series Title |
Lecture Notes in Computer Science |
Abbreviated Series Title |
|
| Series Volume |
3312 |
Series Issue |
|
Edition |
|
| ISSN |
3-540-23738-0 |
ISBN |
|
Medium |
|
| Area |
|
Expedition |
|
Conference |
|
| Notes |
|
Approved |
yes |
| Call Number |
Sapienza @ mari @ Dimtz04 |
Serial |
87 |
| Permanent link to this record |
| |
|
| |
| Author |
Tronci, Enrico; Della Penna, Giuseppe; Intrigila, Benedetto; Venturini Zilli, Marisa |
| Title |
A Probabilistic Approach to Automatic Verification of Concurrent Systems |
Type |
Conference Article |
| Year |
2001 |
Publication |
8th Asia-Pacific Software Engineering Conference (APSEC) |
Abbreviated Journal |
|
| Volume |
|
Issue |
|
Pages |
317-324 |
| Keywords |
|
| Abstract |
The main barrier to automatic verification of concurrent systems is the huge amount of memory required to complete the verification task (state explosion). In this paper we present a probabilistic algorithm for automatic verification via model checking. Our algorithm trades space with time. In particular, when memory is full because of state explosion our algorithm does not give up verification. Instead it just proceeds at a lower speed and its results will only hold with some arbitrarily small error probability. Our preliminary experimental results show that by using our probabilistic algorithm we can typically save more than 30% of RAM with an average time penalty of about 100% w.r.t. a deterministic state space exploration with enough memory to complete the verification task. This is better than giving up the verification task because of lack of memory. |
| Address |
|
| Corporate Author |
|
Thesis |
|
| Publisher |
IEEE Computer Society |
Place of Publication |
Macau, China |
Editor |
|
| Language |
|
Summary Language |
|
Original Title |
|
| Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
0-7695-1408-1 |
ISBN |
|
Medium |
|
| Area |
|
Expedition |
|
Conference |
|
| Notes |
|
Approved |
yes |
| Call Number |
Sapienza @ mari @ apsec01 |
Serial |
43 |
| Permanent link to this record |
| |
|
| |
| Author |
Tronci, Enrico; Della Penna, Giuseppe; Intrigila, Benedetto; Venturini Zilli, Marisa |
| Title |
Exploiting Transition Locality in Automatic Verification |
Type |
Conference Article |
| Year |
2001 |
Publication |
11th IFIP WG 10.5 Advanced Research Working Conference on Correct Hardware Design and Verification Methods (CHARME) |
Abbreviated Journal |
|
| Volume |
|
Issue |
|
Pages |
259-274 |
| Keywords |
|
| Abstract |
In this paper we present an algorithm to contrast state explosion when using Explicit State Space Exploration to verify protocols. We show experimentally that protocols exhibit transition locality. We present a verification algorithm that exploits transition locality as well as an implementation of it within the Mur$\varphi$ verifier. Our algorithm is compatible with all Breadth First (BF) optimization techniques present in the Mur$\varphi$ verifier and it is by no means a substitute for any of them. In fact, since our algorithm trades space with time, it is typically most useful when one runs out of memory and has already used all other state reduction techniques present in the Mur$\varphi$ verifier. Our experimental results show that using our approach we can typically save more than 40% of RAM with an average time penalty of about 50% when using (Mur$\varphi$) bit compression and 100% when using bit compression and hash compaction. |
| Address |
|
| Corporate Author |
|
Thesis |
|
| Publisher |
Springer |
Place of Publication |
Livingston, Scotland, UK |
Editor |
Margaria, T.; Melham, T.F. |
| Language |
|
Summary Language |
|
Original Title |
|
| Series Editor |
|
Series Title |
Lecture Notes in Computer Science |
Abbreviated Series Title |
|
| Series Volume |
2144 |
Series Issue |
|
Edition |
|
| ISSN |
3-540-42541-1 |
ISBN |
|
Medium |
|
| Area |
|
Expedition |
|
Conference |
|
| Notes |
|
Approved |
yes |
| Call Number |
Sapienza @ mari @ charme01 |
Serial |
44 |
| Permanent link to this record |
| |
|
| |
| Author |
Della Penna, Giuseppe; Intrigila, Benedetto; Tronci, Enrico; Venturini Zilli, Marisa |
| Title |
Synchronized Regular Expressions |
Type |
Journal Article |
| Year |
2002 |
Publication |
Electr. Notes Theor. Comput. Sci. |
Abbreviated Journal |
|
| Volume |
62 |
Issue |
|
Pages |
195-210 |
| Keywords |
|
| Abstract |
Text manipulation is one of the most common tasks for everyone using a computer. The increasing number of textual information in electronic format that every computer user collects everyday stresses the need of more powerful tools to interact with texts. Indeed, much work has been done to provide nonprogramming tools that can be useful for the most common text manipulation issues. Regular Expressions (RE), introduced by Kleene, are well–known in the formal language theory. RE received several extensions, depending on the application of interest. In almost all the implementations of RE search algorithms (e.g. the egrep [A] UNIX command, or the Perl [17] language pattern matching constructs) we find backreferences (as defind in [1]), i.e. expressions that make reference to the string matched by a previous subexpression. Generally speaking, it seems that all the kinds of synchronizations between subexpressions in a RE can be very useful when interacting with texts. Therefore, we introduce the Synchronized Regular Expressions (SRE) as a derivation of the Regular Expressions. We use SRE to present a formal study of the already known backreferences extension, and of a new extension proposed by us, which we call the synchronized exponents. Moreover, since we are talking about formalisms that should have a practical utility and can be used in the real world, we have the problem of how to present SRE to the final users. Therefore, in this paper we also propose a user–friendly syntax for SRE to be used in implementations of SRE–powered search algorithms. |
| 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 |
TOSCA 2001, Theory of Concurrency, Higher Order Languages and Types |
Approved |
yes |
| Call Number |
Sapienza @ mari @ entcs02 |
Serial |
46 |
| Permanent link to this record |
| |
|
| |
| Author |
Barbanera, Franco; Dezani-Ciancaglini, Mariangiola; Salvo, Ivano; Sassone, Vladimiro |
| Title |
A Type Inference Algorithm for Secure Ambients |
Type |
Journal Article |
| Year |
2002 |
Publication |
Electronic Notes in Theoretical Computer Science |
Abbreviated Journal |
|
| Volume |
62 |
Issue |
|
Pages |
83-101 |
| Keywords |
|
| Abstract |
We consider a type discipline for the Ambient Calculus that associates ambients with security levels and constrains them to be traversed by or opened in ambients of higher security clearance only. We present a bottom-up algorithm that, given an untyped process P, computes a minimal set of constraints on security levels such that all actions during runs of P are performed without violating the security level priorities. Such an algorithm appears to be a prerequisite to use type systems to ensure security properties in the web scenario. |
| Address |
|
| Corporate Author |
|
Thesis |
|
| Publisher |
Elsevier |
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 |
TOSCA 2001, Theory of Concurrency, Higher Order Languages and Types |
Approved |
yes |
| Call Number |
Sapienza @ mari @ Barbanera-Dezani-Salvo-Sassone:01 |
Serial |
73 |
| Permanent link to this record |
| |
|
| |
| Author |
Coppo, Mario; Dezani-Ciancaglini, Mariangiola; Giovannetti, Elio; Salvo, Ivano |
| Title |
Mobility Types for Mobile Processes in Mobile Ambients |
Type |
Journal Article |
| Year |
2003 |
Publication |
Electr. Notes Theor. Comput. Sci. |
Abbreviated Journal |
|
| Volume |
78 |
Issue |
|
Pages |
|
| Keywords |
|
| Abstract |
We present an ambient-like calculus in which the open capability is dropped, and a new form of “lightweight  process mobility is introduced. The calculus comes equipped with a type system that allows the kind of values exchanged in communications and the access and mobility properties of processes to be controlled. A type inference procedure determines the “minimal  requirements to accept a system or a component as well typed. This gives a kind of principal typing. As an expressiveness test, we show that some well known calculi of concurrency and mobility can be encoded in our calculus in a natural way. |
| 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 @ Coppo-Dezani-Giovannetti-Salvo:03 |
Serial |
74 |
| Permanent link to this record |
