Emanuele Covino

An approach to use FB-AODV with Android

This work talks about an attempt to create a Mobile Ad-hoc NETwork with Android smartphones. We used FBaodv to manage the networks and some bash script to share informations within the networks. MANET was tested by simple applications to view local neighbors, to send sms over the networks.

Bayesian Cognitive Diagnosis in Believable Multiagent Systems

Multiagent systems are computational systems in which several agents interact either to solve a common problem or to achieve independent goals, by coordinating with each other. Agents are computational entities aimed at autonomously achieving some goal or assigned task; they can compete, cooperate, communicate and negotiate with each other. A rational agent takes decisions about how to behave in a given circumstance by reasoning on its own mental state, that is on first order beliefs and goals. When it is programmed so as to show a ‘socially intelligent’ behaviour, it considers, in its reasoning, also the mental state of the agents with which it interacts (second and higher order beliefs). Second order beliefs may be acquired through ‘self-introduction’ of agents, may be inherited from stereotypes, may be ascribed according to one’s own beliefs or may be inferred by observing the other agents’ behaviour [Jameson, 1995]. In the absence of any information (for instance, at its entry in the world), the observing agent may start from a default and possibly incomplete model of the other agents: this model will be revised as the interaction proceeds, through a reasoning process that has been named belief ascription or cognitive diagnosis [Lee and Wilks, 1996], [Self, 1993]. The following problems characterize this reasoning process: the behaviour of the observed agent may be ‘ambiguous’, and subject to different interpretations; in this case, the most likely hypothesis has to be selected, by leaving aside alternatives for future revisions; this behaviour may be ‘contradictory’, for different reasons: because the observed agent may change its mind, because it may lie or just because a previous interpretation was incorrect.

A predicative approach to the classification problem

We harmonize many time-complexity classes DTIMEF ( f ( n )) ( f ( n ) [ges ] n ) with the PR functions (at and above the elementary level) in a transfinite hierarchy of classes of functions [Tscr ] α . Class [Tscr ] α is obtained by means of unlimited operators, namely: a variant Π of the predicative or safe recursion scheme, introduced by Leivant, and by Bellantoni and Cook, if α is a successor; and constructive diagonalization if α is a limit. Substitution ( SBST ) is discarded because the time complexity classes are not closed under this scheme. [Tscr ] α is a structure for the PR functions finer than [Escr ] α , to the point that we have [Tscr ] e 0 = [Escr ] 3 (elementary functions). Although no explicit use is made of hierarchy functions, it is proved that f ( n ) ∈ [Tscr ] α implies f ( n ) [les ] n G α ( n ) , where G α belongs to the slow growing hierarchy (of functions) studied, in particular, by Girard and Wainer.

HSFS: A Compress Filesystem for Metadata Files

In this paper we propose a solution to improve the search among compress data. A Linux filesystem have been implemented by combining the advantages of squashfs (compression) and hixosfs (for research). We test our idea with DICOM file used to store medical images.

Extending the Implicit Computational Complexity Approach to the Sub-elementary Time-Space Classes

A resource-free characterization of some complexity classes is given by means of the predicative recursion and constructive diagonalization schemes, and of restrictions to substitution. Among other classes, we predicatively harmonize in the same hierarchy ptimef, the class Ɛ of the elementary functions, and classes DTIMESPACEF(np, nq).

A Refinement of the μ-measure for Stack Programs

Abstract We analyze the complexity of a programming language operating on stacks, introducing a syntactical measure σ such that to each program P a natural number σ( P ) is assigned; the measure considers the influence on the complexity of programs of nesting loops and, simultaneously, of sequences of non-size-increasing subprograms. We prove that functions computed by stack programs of σ measure n have a length bound b∈ E n+2 (the n+2-th Grzegorczyk class), that is |f( w → )|≤b(| w → |) . This result represents an improvement with respect to the bound obtained via the μ-measure presented in [L. Kristiansen and K.-H. Niggl, On the computational complexity of imperative programming languages. Theoretical Computer Science, to appear].

Syntactic Characterization in LISP of the Polynominal Complexity Classes and Hierarchy

The definition of a class C of functions is syntactic if membership to C can be decided from the construction of its elements. Syntactic characterizations of PTIMEF, of PSPACEF, of the polynomial hierarchy PH, and of its subclasses Δ n p are presented. They are obtained by progressive restrictions of recursion in Lisp, and may be regarded as predicative according to a foundational point raised by Leivant.