Search results for "Theoretical Computer Science"
showing 10 items of 1151 documents
Coherence Checking and Propagation of Lower Probability Bounds
2003
In this paper we use imprecise probabilities, based on a concept of generalized coherence (g-coherence), for the management of uncertain knowledge and vague information. We face the problem of reducing the computational difficulties in g-coherence checking and propagation of lower conditional probability bounds. We examine a procedure, based on linear systems with a reduced number of unknowns, for the checking of g-coherence. We propose an iterative algorithm to determine the reduced linear systems. Based on the same ideas, we give an algorithm for the propagation of lower probability bounds. We also give some theoretical results that allow, by suitably modifying our algorithms, the g-coher…
Structural Knowledge Extraction from Mobility Data
2016
Knowledge extraction has traditionally represented one of the most interesting challenges in AI; in recent years, however, the availability of large collections of data has increased the awareness that “measuring” does not seamlessly translate into “understanding”, and that more data does not entail more knowledge. We propose here a formulation of knowledge extraction in terms of Grammatical Inference (GI), an inductive process able to select the best grammar consistent with the samples. The aim is to let models emerge from data themselves, while inference is turned into a search problem in the space of consistent grammars, induced by samples, given proper generalization operators. We will …
Decentralization and heterogeneity in complex adaptative systems
2015
Purpose – Following a bacterial-based modeling approach, the authors want to model and analyze the impact of both decentralization and heterogeneity on group behavior and collective learning. The paper aims to discuss these issues. Design/methodology/approach – Inspired by bacterial conjugation, the authors have defined an artificial society in which agents’ strategies adapt to changes in resources location, allowing migration, and survival in a dynamic sugarscape-like scenario. To study the impact of these variables the authors have simulated a scenario in which resources are limited and localized. The authors also have defined three constraints in genetic information processing (inhibiti…
An inductive learning perspective on automated generation of feature models from given product specifications
2018
For explicit representation of commonality and variability of a product line, a feature model is mostly used. An open question is how a feature model can be inductively learned in an automated way from a limited number of given product specifications in terms of features.We propose to address this problem through machine learning, more precisely inductive generalization from examples. However, no counter-examples are assumed to exist. Basically, a feature model needs to be complete with respect to all the given example specifications. First results indicate the feasibility of this approach, even for generating hierarchies, but many open challenges remain.
Quantum Query Algorithms for Conjunctions
2010
Every Boolean function can be presented as a logical formula in conjunctive normal form. Fast algorithm for conjunction plays significant role in overall algorithm for computing arbitrary Boolean function. First, we present a quantum query algorithm for conjunction of two bits. Our algorithm uses one quantum query and correct result is obtained with a probability p = 4/5, that improves the previous result. Then, we present the main result - generalization of our approach to design efficient quantum algorithms for computing conjunction of two Boolean functions. Finally, we demonstrate another kind of an algorithm for conjunction of two bits, that has a correct answer probability p = 9/10. Th…
Run-time profiling of functional logic programs
2005
In this work, we introduce a profiling scheme for modern functional logic languages covering notions like laziness, sharing, and non-determinism. Firstly, we instrument a natural (big-step) semantics in order to associate a symbolic cost to each basic operation (e.g., variable updates, function unfoldings, case evaluations). While this cost semantics provides a formal basis to analyze the cost of a computation, the implementation of a cost-augmented interpreter based on it would introduce a huge overhead. Therefore, we also introduce a sound transformation that instruments a program such that its execution—under the standard semantics—yields not only the corresponding results but also the a…
Quantum Security Proofs Using Semi-classical Oracles
2019
We present an improved version of the one-way to hiding (O2H) Theorem by Unruh, J ACM 2015. Our new O2H Theorem gives higher flexibility (arbitrary joint distributions of oracles and inputs, multiple reprogrammed points) as well as tighter bounds (removing square-root factors, taking parallelism into account). The improved O2H Theorem makes use of a new variant of quantum oracles, semi-classical oracles, where queries are partially measured. The new O2H Theorem allows us to get better security bounds in several public-key encryption schemes.
On the Influence of PRNGs on Data Distribution
2012
The amount of digital information produced grows rapidly and constantly. Storage systems use clustered architectures designed to store and process this information efficiently. Their use introduces new challenges in storage systems development, like load-balancing and data distribution. A variety of randomized solutions handling data placement issues have been proposed and utilized. However, to the best of our knowledge, there has not yet been a structured analysis of the influence of pseudo random number generators (PRNGs) on the data distribution. In the first part of this paper we consider Consistent Hashing [1] as a combination of two consecutive phases: distribution of bins and distrib…
Improved Magic Ink Signatures Using Hints
1999
We introduce two improvements to the recently proposed so called magic ink DSS signatures. A first improvement is that we reduce the overhead for tracing without noticeably increasing any other cost. The tracing cost is linear in the number of generated signatures in the original proposal; our improved version reduces this to a logarithmic cost in the common case. A second improvement is that we introduce a method for determining whether forged currency is in circulation, without affecting the privacy of honest users. Our improvements rely on our introducing a so called hint value. This is an encryption of the signature transcript received, submitted by the signature receiver. Part of the p…
A closer look at mirrors and quotients of Calabi-Yau threefolds
2016
Let X be the toric variety (P1)4 associated with its four-dimensional polytope 1. Denote by X˜ the resolution of the singular Fano variety Xo associated with the dual polytope 1o. Generically, anticanonical sections Y of X and anticanonical sections Y˜ of X˜ are mirror partners in the sense of Batyrev. Our main result is the following: the Hodge-theoretic mirror of the quotient Z associated to a maximal admissible pair (Y, G) in X is not a quotient Z˜ associated to an admissible pair in X˜ . Nevertheless, it is possible to construct a mirror orbifold for Z by means of a quotient of a suitable Y˜. Its crepant resolution is a Calabi-Yau threefold with Hodge numbers (8, 4). Instead, if we star…