| Records |
| 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 |
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| Volume |
62 |
Issue |
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Pages |
195-210 |
| Keywords |
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| 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. |
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TOSCA 2001, Theory of Concurrency, Higher Order Languages and Types |
Approved |
yes |
| Call Number |
Sapienza @ mari @ entcs02 |
Serial |
46 |
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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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yes |
| Call Number |
Sapienza @ mari @ DIMTZ04j |
Serial |
91 |
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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) |
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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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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 |
Della Penna, Giuseppe; Intrigila, Benedetto; Melatti, Igor; Tronci, Enrico; Venturini Zilli, Marisa |
| Title |
Finite horizon analysis of Markov Chains with the Mur$\varphi$ verifier |
Type |
Journal Article |
| Year |
2006 |
Publication |
Int. J. Softw. Tools Technol. Transf. |
Abbreviated Journal |
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| Volume |
8 |
Issue |
4 |
Pages |
397-409 |
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| Abstract |
In this paper we present an explicit disk-based verification algorithm for Probabilistic Systems defining discrete time/finite state Markov Chains. Given a Markov Chain and an integer k (horizon), our algorithm checks whether the probability of reaching an error state in at most k steps is below a given threshold. We present an implementation of our algorithm within a suitable extension of the Mur$\varphi$ verifier. We call the resulting probabilistic model checker FHP-Mur$\varphi$ (Finite Horizon Probabilistic Mur$\varphi$). We present 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 handle systems that are out of reach for PRISM, namely those involving arithmetic operations on the state variables (e.g. hybrid systems). |
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Springer-Verlag |
Place of Publication |
Berlin, Heidelberg |
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1433-2779 |
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Approved |
yes |
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Sapienza @ mari @ Dimtz06 |
Serial |
78 |
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| 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 |
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| Volume |
78 |
Issue |
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Pages |
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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. |
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yes |
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Sapienza @ mari @ Coppo-Dezani-Giovannetti-Salvo:03 |
Serial |
74 |
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| 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 |
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| Volume |
62 |
Issue |
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Pages |
83-101 |
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| 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. |
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Elsevier |
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TOSCA 2001, Theory of Concurrency, Higher Order Languages and Types |
Approved |
yes |
| Call Number |
Sapienza @ mari @ Barbanera-Dezani-Salvo-Sassone:01 |
Serial |
73 |
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| 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 |
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Issue |
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Pages |
317-324 |
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| 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. |
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IEEE Computer Society |
Place of Publication |
Macau, China |
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0-7695-1408-1 |
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Approved |
yes |
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Sapienza @ mari @ apsec01 |
Serial |
43 |
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| Author |
Della Penna, Giuseppe; Intrigila, Benedetto; Tronci, Enrico; Venturini Zilli, Marisa |
| Title |
Synchronized regular expressions |
Type |
Journal Article |
| Year |
2003 |
Publication |
Acta Inf. |
Abbreviated Journal |
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| Volume |
39 |
Issue |
1 |
Pages |
31-70 |
| Keywords |
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| 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 also increases the need of more powerful tools to interact with texts. Indeed, much work has been done to provide simple and versatile tools that can be useful for the most common text manipulation tasks. Regular Expressions (RE), introduced by Kleene, are well known in the formal language theory. RE have been extended in various ways, depending on the application of interest. In almost all the implementations of RE search algorithms (e.g. the egrep [15] UNIX command, or the Perl [20] language pattern matching constructs) we find backreferences, i.e. expressions that make reference to the string matched by a previous subexpression. Generally speaking, it seems that all kinds of synchronizations between subexpressions in a RE can be very useful when interacting with texts. In this paper we introduce the Synchronized Regular Expressions (SRE) as an extension 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 dealing with formalisms that should have a practical utility and be used in real applications, 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. |
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yes |
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Sapienza @ mari @ actainf03 |
Serial |
39 |
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| Author |
Mancini, Toni ; Mari, Federico ; Massini, Annalisa; Melatti, Igor; Tronci, Enrico |
| Title |
System Level Formal Verification via Distributed Multi-Core Hardware in the Loop Simulation |
Type |
Conference Article |
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2014 |
Publication |
Proc. of the 22nd Euromicro International Conference on Parallel, Distributed and Network-Based Processing |
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Euromicro International Conference on Parallel, Distributed and Network-Based Processing |
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IEEE Computer Society |
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no |
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Sapienza @ melatti @ |
Serial |
118 |
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Tronci, E.; Mancini, T.; Mari, F.; Melatti, I.; Jacobsen, R. H.; Ebeid, E.; Mikkelsen, S. A.; Prodanovic, M.; Gruber, J. K.; Hayes, B. |
| Title |
SmartHG: Energy Demand Aware Open Services for Smart Grid Intelligent Automation |
Type |
Conference Article |
| Year |
2014 |
Publication |
Proceedings of the Work in Progress Session of SEAA/DSD 2014 |
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978-3-902457-40-0 |
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Sapienza @ mari @ |
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119 |
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