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Wyświetlanie 1-4 z 4
Tytuł:
Mining online auction social networks for reputation and recommendation
Autorzy:
Morzy, M.
Wierzbicki, A.
Papadopoulos, A. N.
Powiązania:
https://bibliotekanauki.pl/articles/970827.pdf
Data publikacji:
2009
Wydawca:
Polska Akademia Nauk. Instytut Badań Systemowych PAN
Tematy:
online auctions
reputation
recommendations
Opis:
Online auctions are quickly becoming one of the leading branches of e-commerce. Unfortunately, online auctions attract many fraudulent activities. Reputation systems are crucial for guaranteeing fairness of trade and reliability of service. Currently used reputation systems offer little protection from malevolent contractors. In this paper we present a new method for mining the reputation of sellers in online auctions. We devise two independent measures that assess reliability and questionability of sellers in parallel, leading to the concept of positive and negative reputation. To compute these measures we construct an S-graph which reflects the social linkage between sellers and buyers. We use both explicit and implicit feedbacks provided by auction participants, carefully identifying missing feedbacks that have been purposefully left out. Based on reputation estimates the community of online auction participants can detect misbehaving contractors and counteract fraud. Thus, the application of social information about reputation of contractors can be perceived as recommendations. Experimental evaluation of our proposal proves the feasibility and usefulness of the presented approach.
Źródło:
Control and Cybernetics; 2009, 38, 1; 87-106
0324-8569
Pojawia się w:
Control and Cybernetics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Bidding languages for auctions of divisible goods
Autorzy:
Kaleta, M.
Powiązania:
https://bibliotekanauki.pl/articles/206521.pdf
Data publikacji:
2012
Wydawca:
Polska Akademia Nauk. Instytut Badań Systemowych PAN
Tematy:
bidding languages
auctions
market mechanism design
Opis:
Bidding languages are well-defined for combinatorial auctions. However, the auctions of divisible goods are quite common in practice. In contrast to combinatorial auctions, the feasible volumes of the offers are continuous in the case of divisible commodities. Such auctions are called continuous auctions. In the paper we introduce three families of bidding languages for continuous auctions. They are based on the concepts derived from the combinatorial auctions. We generalize the language families based on goods, bids, and some mixture of both of them, to the continuous case. We also analyze fundamental properties of the new languages. Simple examples, reflecting the complementarity and substitutability, are provided with exemplary representations in different languages.
Źródło:
Control and Cybernetics; 2012, 41, 4; 799-816
0324-8569
Pojawia się w:
Control and Cybernetics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Quantitative analysis of internet auctions advertising features: an empirical study
Autorzy:
Wojciechowski, A.
Warczynski, P.
Powiązania:
https://bibliotekanauki.pl/articles/205589.pdf
Data publikacji:
2012
Wydawca:
Polska Akademia Nauk. Instytut Badań Systemowych PAN
Tematy:
on-line auctions
price effectiveness
bidder behaviour
Opis:
Internet auction sites are trading platforms with huge number of visitors who may become customers. On-line auctions allow users to buy and sell products without geographical borders, as in majority of cases ordered products are delivered by surface mail. The aim of the study was to collect substantial amount of data describing on-line auctions in a variety of attributes, and customer behaviour. We provide quantitative arguments in the discussion on effectiveness of promotional features used in on-line auctions. Experimental survey showed that almost 2/3 of the total number of observed auctions were indexed in five top (out of 23) product categories. Noticeable difference in sale effectiveness was observed for particular days of week and hours of auction termination. On Saturdays and Sundays the chance to terminate an auction with transaction was 17.72% and 19.46%, respectively, while on Tuesdays – Orly 14.29%. The highest ratio of successful auction-transaction against total number of auctions ending within particular hour occurred between 19:00 and 22:00. Our approximation of job lot transactions showed that it was a common practice among bidders to buy more than one product form one seller. In the reference period about 25% of all transactions could be qualified as job-lot ones. A miniature image displayed by auction title appeared the cheapest and most price effective form of advertising an auction while promoting on action site main page was the most effective in increasing visits/displays (by 2341%), yet, the high price of this advertising feature may pay back only if customers’ visits turn into transactions.
Źródło:
Control and Cybernetics; 2012, 41, 4; 851-865
0324-8569
Pojawia się w:
Control and Cybernetics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Minimisation of public debt servicing costs based on nonlinear mathematical programming approach
Autorzy:
Klukowski, L.
Kuba, E.
Powiązania:
https://bibliotekanauki.pl/articles/206515.pdf
Data publikacji:
2001
Wydawca:
Polska Akademia Nauk. Instytut Badań Systemowych PAN
Tematy:
minimisation of servicing costs of public debt
optimisation approach in public debt management
profitability minimisation of debt instruments sold at auctions
Opis:
The paper presents formulations of optimisation problems for minimisation of servicing cost of government debt instruments (T-bills and T-bonds) issued in Poland and examples of their applications. The first of these problems allows for determining the structure of T-bills with different maturities - from 1 to 52 weeks (sold at multiprice auction), which minimise their servicing cost. This cost (criterion function) is based on T-bills profitability determined by compound rate of return (CRR). The constraints of the task express: * minimum receipts to the State Budget, * maximal profitability, * average maturity, and * minimal and maximal amount for each type of bills. The generalisation of this problem for some series of (consecutive) auctions is also discussed. The second task makes it possible to determine optimal structure of T-bonds using a similar (but more complex) form of the criterion function and more extensive set of constraints. The problems presented are of discrete and non-linear form and in result - rather difficult to solve in real time (during the auction). Therefore, some continuos approximations of these problems based on polynomials determined with the use of least squares method are suggested. Such an approach makes it possible to obtain an optimal solution in several minutes using Excel spreadsheet (package solver) and PC computer. Examples of actual problems for T-bills and T-bonds, based on data for the year 2000 are presented, too. The application of optimisation methods resulted in (relative) gain measured by a criterion function equal to about 1% (annual costs of the domestic debt equals about [3 * 10^9] US$).
Źródło:
Control and Cybernetics; 2001, 30, 1; 99-114
0324-8569
Pojawia się w:
Control and Cybernetics
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-4 z 4

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