Improving the Efficiency of Inductive Logic Programming Through the Use of Query Packs

Inductive logic programming, or relational learning, is a powerful paradigm for machine learning or data mining. However, in order for ILP to become practically useful, the efficiency of ILP systems must improve substantially. To this end, the notion of a query pack is introduced: it structures sets of similar queries. Furthermore, a mechanism is described for executing such query packs. A complexity analysis shows that considerable efficiency improvements can be achieved through the use of this query pack execution mechanism. This claim is supported by empirical results obtained by incorporating support for query pack execution in two existing learning systems

Non-equilibrium states of a photon cavity pumped by an atomic beam

We consider a beam of two-level randomly excited atoms that pass one-by-one through a one-mode cavity. We show that in the case of an ideal cavity, i.e. no leaking of photons from the cavity, the pumping by the beam leads to an unlimited increase in the photon number in the cavity. We derive an expression for the mean photon number for all times. Taking into account leaking of the cavity, we prove that the mean photon number in the cavity stabilizes in time. The limiting state of the cavity in this case exists and it is independent of the initial state. We calculate the characteristic functional of this non-quasi-free non-equilibrium state. We also calculate the energy flux in both the ideal and open cavity and the entropy production for the ideal cavity.Comment: Corrected energy production calculations and made some changes to ease the readin

Conditions for the local manipulation of Gaussian states.

Published versio

The characterization of Gaussian operations and Distillation of Gaussian States

We characterize the class of all physical operations that transform Gaussian states to Gaussian states. We show that this class coincides with that of all operations which can be performed on Gaussian states using linear optical elements and homodyne measurements. For bipartite systems we characterize the processes which can be implemented by local operations and classical communication, as well as those that can be implemented using positive partial transpose preserving maps. As an application, we show that Gaussian states cannot be distilled by local Gaussian operations and classical communication. We also define and characterize positive (but not completely positive) Gaussian maps.Comment: 8 pages, revtex4; v4: published version; v3: more details on V(gamma), some typos corrected, formulations clarifie

Entanglement concentration of continuous variable quantum states

We propose two probabilistic entanglement concentration schemes for a single copy of two-mode squeezed vacuum state. The first scheme is based on the off-resonant interaction of a Rydberg atom with the cavity field while the second setup involves the cross Kerr interaction, auxiliary mode prepared in a strong coherent state and a homodyne detection. We show that the continuous-variable entanglement concentration allows us to improve the fidelity of teleportation of coherent states.Comment: 7 pages, 7 figure

Driving non-Gaussian to Gaussian states with linear optics

Published versio

Copying garbage collection for the WAM: To mark or not to mark?

Garbage collection by copying is becoming more and more popular for Prolog. In principle copying requires a marking phase in order to be safe. However, some systems use a copying garbage collector without marking prior to copying, and instead postpone the copying of cells that might cause problems. Such systems always perform minor collections, and it is not clear whether postponing works for major collections. Postponin

Heap Garbage Collection in XSB: Practice and Experience

Starting from a theoretical understanding of the usefulness logic of a logic programming system with built-in tabling, and from a collector that did not take the characteristics of a tabled abstract machine into account we have build two heap garbage collectors (one mark&slide, one mark&copy) for XSB on top of the CHAT implementation model for the suspension/resumption of consumers. Based on this experience we discuss implementation issues that are general to heap garbage collection for the WAM and also issues that are specific to an implementation with tabling: as such, this paper documents our own implementation and can serve as guidance for anyone attempting a similar feat. We report on the behaviour of the garbage collectors on different kinds of programs. We also present figures on the extent of internal fragmentation and the effectiveness of early reset in Prolog systems with and without tabling