Regression with Linear Factored Functions

Many applications that use empirically estimated functions face a curse of dimensionality, because the integrals over most function classes must be approximated by sampling. This paper introduces a novel regression-algorithm that learns linear factored functions (LFF). This class of functions has structural properties that allow to analytically solve certain integrals and to calculate point-wise products. Applications like belief propagation and reinforcement learning can exploit these properties to break the curse and speed up computation. We derive a regularized greedy optimization scheme, that learns factored basis functions during training. The novel regression algorithm performs competitively to Gaussian processes on benchmark tasks, and the learned LFF functions are with 4-9 factored basis functions on average very compact.Comment: Under review as conference paper at ECML/PKDD 201

Test of the ALICE DDL: Test setups and Test of ALICE DDL Integration to ALICE TPC test system

Presentation made at the 4th Workshop on Electronics for LHC Experiments, INFN Rome, 21-25 September 1998.The Detector Data Link (DDL) has been developed to constitute a standard interface between the ALICE sub-detectors and the DAQ system.In this paper we present the test environment and the application software library made for supporting the DDL development and its integration into the ALICE detector system. The test setups contain VME64 crates, MVME processor cards, a VMETRO analyser, a logic-analyser and Read-out-Receiver (RORC) andDestination-Interface-Unit (DIU) cards. They made possible to measure the maximum throughput of the full read-out chain and also to measurethe transmission latencies. They support the functional and long-term stability tests as well

An impossibility theorem for paired comparisons

In several decision-making problems, alternatives should be ranked on the basis of paired comparisons between them. We present an axiomatic approach for the universal ranking problem with arbitrary preference intensities, incomplete and multiple comparisons. In particular, two basic properties -- independence of irrelevant matches and self-consistency -- are considered. It is revealed that there exists no ranking method satisfying both requirements at the same time. The impossibility result holds under various restrictions on the set of ranking problems, however, it does not emerge in the case of round-robin tournaments. An interesting and more general possibility result is obtained by restricting the domain of independence of irrelevant matches through the concept of macrovertex.Comment: 18 pages, 4 figure

PCI Based Read-out Receiver Card in the ALICE DAQ System

The Detector Data Link (DDL) is the high-speed optical link for the ALICE experiment. This link shall transfer the data coming from the detectors at 100 MB/s rate. The main components of the link have been developed: the destination Interface Unit (DIU), the Source Interface Unit (SIU) and the Read-out Receiver Card (RORC). The first RORC version is based on the VME bus. The performance tests show that the maximum VME bandwidth could be reached. Meanwhile the PCI bus became very popular and is used in many platforms. The development of a PCI-based version has been started. The document describes the prototype version in three sections. An overview explains the main purpose of the card: to provide an interface between the DDL and the PCI bus. Acting as a 32bit/33MHz PCI master the card is able to write or read directly to or from the system memory from or to the DDL, respectively. Beside these functions the card can also be used as an autonomous data generator. The card has been designed to be well adapted to applications, which require small software overhead such the high-speed data acquisition systems. The implementation of the firmware will be presented. For the logic design we are using VHDL and schematic draw. Software library routines were written in C and are available on Linux OS. The results of performance measurements will be available to allow the comparison between the VME-RORC and PCI-RORC. In the conclusion the future plans and the idea of the improved (64bit/66MHz) PCI-RORC will be shown

The ALICE detector data link

The ALICE detector data link has been designed to cover all the needs for data transfer between the detector and the data-acquisition system. It is a 1 Gbit/s, full-duplex, multi-purpose fibre optic link that can be used as a medium for the bi-directional transmission of data blocks between the front-end electronics and the data- acquisition system and also for the remote control and test of the front-end electronics, In this paper the concept, the protocol, the specific test tools, the prototypes of the detector data link and the read-out receiver card, their application in the ALICE-TPC test system and the integration with the DATE software are presented. The test results on the performance are also shown. (14 refs)

Characterization of the Row Geometric Mean Ranking with a Group Consensus Axiom

An axiomatic approach is applied to the problem of extracting a ranking of the alternatives from a pairwise comparison ratio matrix. The ordering induced by row geometric mean method is proved to be uniquely determined by three independent axioms, anonymity (independence of the labelling of alternatives), responsiveness (a kind of monotonicity property) and aggregation invariance, which requires the preservation of group consensus, that is, the pairwise ranking between two alternatives should remain unchanged if unanimous individual preferences are combined by geometric mean.Comment: 17 pages, 2 figure

Upper Limit of D0 Production in Central Pb-Pb Collisions at 158A GeV

Results are presented from a search for the decays D0 -> Kmin piplus and D0bar -> Kplus pimin in a sample of 3.8x10^6 central Pb-Pb events collected with a beam energy of 158A GeV by NA49 at the CERN SPS. No signal is observed. An upper limit on D0 production is derived and compared to predictions from several models.Comment: REVTEX 5 pages, 4 figure

Rapidity and energy dependence of the electric charge correlations in A+A collisions at the SPS energies

Results from electric charge correlations studied with the Balance Function method in A+A collisions from 20\emph{A} to 158\emph{A} GeV are presented in two different rapidity intervals: In the mid-rapidity region we observe a decrease of the width of the Balance Function distribution with increasing centrality of the collision, whereas this effect vanishes in the forward rapidity region. Results from the energy dependence study in central Pb+Pb collisions show that the narrowing of the Balance Function expressed by the normalised width parameter \textit{W} increases with energy towards the highest SPS and RHIC energies. Finally we compare our experimental data points with predictions of several models. The hadronic string models UrQMD and HIJING do not reproduce the observed narrowing of the Balance Function. However, AMPT which contains a quark-parton transport phase before hadronization can reproduce the narrowing of the BF's width with centrality. This confirms the proposed sensitivity of the Balance Function analysis to the time of hadronization.Comment: Submitted in Phys. Rev.