1,354,842 research outputs found
Attraverso e oltre la fonetica e la fonologia, ovvero "l'enfance retrouvée à volonté"
No full textA LOCAL APPROACH FOR TEMPORAL MODEL CHECKING OF JAVA BYTECODE
No full textAbstractModern computing applications require highly reliable software systems, but current validation techniques, like testing, fail to assure an adequate level of correctness. We present a model checking procedure to verify a subset of the Java virtual machine language (JVML) with respect to properties expressed by a temporal logic. A tableau-based method is developed to prove the satisfaction of a formula: by this local approach a program computation is checked only if involved in the goal of the property verification. A special symbol ⊥ is introduced to represent “unknown’’ values, and computations are performed in a symbolic way exploiting the set of guards present in the formulae to refine possible unknown values. This kind of abstraction cuts the state explosion of the programs and it is applicable to check arbitrary formulae, but the result of the verification has an imprecision degree depending on the number of unknown values manipulated during each symbolic computation
Extended pointers for memory protection in single address space systems
No full textWith reference to a single address space paradigm of memory addressing, we identify a set of mechanisms aimed at preserving the integrity of the virtual space of a given process from erroneous or fraudulent access attempts originated from other processes. These mechanisms guarantee a level of protection that is, in many respects, superior to that of a traditional multiple address space environment. We introduce extended pointers as a generalization of the concept of a memory address, which includes a password and an access authorization. A universally known, parametric one-way function is used to assign passwords. A specialized address translation circuitry supports memory reference and protection at the hardware level. A small set of protection primitives forms the process interface of the protection system. An indication of the flexibility of the proposed protection paradigm is given by applying extended pointers to the solution of a variety of protection problems
COMPOSITIONALITY AND LOCALITY FOR IMPROVING MODEL CHECKING IN THE SELECTIVE MU-CALCULUS
No full textAbstractModel checking is an automatic technique for verifying properties of finite concurrent systems on a structure that represents the states of the system; the crucial point of the technique is to avoid the computation of all the possible states. In this paper a method of proof for concurrent systems is presented that combines several approaches to meet the previous goal. The method exploits compositionality issues, in the presence of a parallel composition of processes, to compute at most the states of each sequential process, and not their combinations; moreover the method employs abstraction techniques to compute but a subset of the states of each sequential process. Finally, tableau-based proofs are used to allow the dynamic generation of the system states when needed, taking into account the goal of the formula verification. The tableau system is proved finite, sound and complete, for finite state systems
- …
