Tight Bounds for the Price of Anarchy of Simultaneous First Price Auctions

We study the Price of Anarchy of simultaneous first-price auctions for buyers with submodular and subadditive valuations. The current best upper bounds for the Bayesian Price of Anarchy of these auctions are e/(e-1) [Syrgkanis and Tardos 2013] and 2 [Feldman et al. 2013], respectively. We provide matching lower bounds for both cases even for the case of full information and for mixed Nash equilibria via an explicit construction. We present an alternative proof of the upper bound of e/(e-1) for first-price auctions with fractionally subadditive valuations which reveals the worst-case price distribution, that is used as a building block for the matching lower bound construction. We generalize our results to a general class of item bidding auctions that we call bid-dependent auctions (including first-price auctions and all-pay auctions) where the winner is always the highest bidder and each bidder's payment depends only on his own bid. Finally, we apply our techniques to discriminatory price multi-unit auctions. We complement the results of [de Keijzer et al. 2013] for the case of subadditive valuations, by providing a matching lower bound of 2. For the case of submodular valuations, we provide a lower bound of 1.109. For the same class of valuations, we were able to reproduce the upper bound of e/(e-1) using our non-smooth approach.Comment: 37 pages, 5 figures, ACM Transactions on Economics and Computatio

Zala megye egységes talajtípus bázisának összeállítása klasszifikációs eljárásokkal

Az AGRÁRKLÍMA projekt keretében Zala megye területére vonatkozóan készítettenk talajtípus térképeket a mezô-, és az erdôgazdálkodók részére. A térképek az erre a célra összeállított, geológiai, domborzati, hidrológiai térinformatikai adatbázis, és erdôtervi adatok felhasználásával készültek, kiegészítve a Digitális Kreybig Talajinformációs Rendszer adataival. A termőhelyi erdőtervi és mezőgazdasági adatokat a környezeti változók adataival együtt értékelték, aminek érdekében talajtípusok előfordulásának legjellemzőbb környezeti feltételrendszerét (szignatúrát) határozták meg. A szignatúrák segítségével hierarchikus és nem-hierarchikus osztályozási algoritmusokat dolgoztak ki a talajtípusok térbeli helyének a felismerésére, és értékelték azok pontosságát. A neurális hálózat módszert találták a leghatékonyabb talajtípus előfordulás becslési eljárásnak. Ismert talaj tulajdonságú területek adataival összevetve 67%-os besorolási eredményességet értek el. A térképezési munkával egységes talajtípus adatbázist állítottak elô Zala megye területére

Comparison of skewness-based salient event detector algorithms in speech

In this work, we compare two skewness-based salient event detector algorithms, which can detect transients in human speech signals. Speech transients are characterized by rapid changes in signal energy. The purpose of this study was to compare the identification of transients by two different methods based on skewness calculation in order to develop a method to be used in studying the processing of speech transients in the human brain. The first method, the skewness in variable time (SKV) finds transients using a cochlear model. The skewness of the energy distribution for a variable time window is implemented on artificial neural networks. The second method, the automatic segmentation method for transient detection (RoT) is more speech segmentation-based and developed for detecting transient speech segment ratio in spoken records. In the current study, the test corpus included Hungarian and English speech recorded from different speakers (2 male and 2 female for both languages). Results were compared by the F-measure, the Jaccard similarity index, and the Hamming distance. The results of the two algorithms were also tested against a hand-labeled corpus annotated by linguistic experts for an absolute assessment of the performance of the two methods. Transient detection was tested once for onset events alone and, separately, for onset and offset events together. The results show that in most cases, the RoT method works better on the expert labeled databases. Using F measure with +- 25ms window length the following results were obtained when all type of transient events were evaluated: 0,664 on English and 0,834 on Hungarian. Otherwise, the two methods identify the same stimulus features as the transients also coinciding with those hand-labeled by experts

Márkaszintek kapcsolatrendszerének látható és láthatatlan összefüggései

A szerzők cikkükben a márkaszintek kapcsolatrendszeréből marketingcontrolling megközelítéssel kiolvasható folyamatokra szeretnénk felhívni azok figyelmét, aki ebben a témában és területen érintettek a gyakorlatban és az elméletben, vagy mindkettőben egyaránt

Model-based Angiogenic Inhibition of Tumor Growth using Adaptive Fuzzy Techniques

Fighting tumors is one of the most important problems of medical research. In this paper, antiangiogenic cancer therapy is investigated through its mathematical model.This tumor treatment method targets the endothelium of a growing tumor and belongs to the targeted molecular therapies.The aim of the therapy is not to eliminate the entire tumor,but to decrease the tumor to a minimal volume. An advantage of applying antiangiogenic treatment is that tumor cells show lower tendency of becoming resistant to the applied drugs.Adaptive fuzzy control is implemented for a simplified model to elaborate a control technique which is able to handle the effects of parameter perturbations and uncertainties while keeping the daily and total inhibitor inlet under a given limit

Comparison of Path Tracking Flat Control and Working Point Linearization Based Set Point Control of Tumor Growth with Angiogenic Inhibition

Targeted molecular therapies (TMT) represent new perspectives in cancer treatment, fighting against the specific characteristic of the investigated tumor. Antiangiogenic therapy represents a specific TMT and its role is to stop the angiogenesis of the tumor, the process of forming new blood vessels; hence, to stop tumor growth. Proper control algorithms for tumor growth control with angiogenic inhibition are analyzed in the current article in order to find optimal therapeutic protocols. Two slightly different approaches are compared: nonlinear control by exact linearization with path tracking control, and linear control by working point linearization with set point control. The control strategies are compared in terms of the characteristics of the input signal (the inhibitor, drug intake) that is crucial if the therapy will be put into practice