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Svenska stadskärnor under coronakrisen. En studie av tre svenska stadskärnors samverkansstrukturer under covid-19 pandemin 2020 / Swedish cities during the corona crisis. A study of three swedish cities collaboration structures during the covid-19 pandemic 2020Lundbäck, Axel, Simonian, Sunny January 2020 (has links)
Till följd av covid-19 pandemin har många stadskärnor drabbats av stora omsättningsförluster inäringslivet. Kommunen och verksamheterna som utgör stadskärnan står idag inför stora utmaningar,men också inför eventuella möjligheter. Denna uppsats syftar till att belysa hur samverkansrelationer inomstadsutvecklingsarbetet kan agera som beredskap i kriser samt vilka utvecklingsmöjligheter som krisen gerupphov till. Studien görs på tre stadskärnor med varierande grad av samverkan: Kalmar, Ronneby och Visby.Resultaten visade överväldigande tydligt att samarbete mellan kommun, näringsliv samt fastighetsägare istaden upplevs som en form av beredskap. Det är därmed ytterst viktigt att satsa på att skapa godasamverkansrelationer inom staden i goda tider för att skapa förutsättningar för effektiv krishantering. Studien har funnit att det finns vissa framgångsfaktorer som är angelägna för en stadskärna att beakta i sinutveckling. Dessa är vikten av förtroende mellan aktörer och personer, etablerade kommunikationsvägarsamt långsiktig och strategisk planering för stärkt efterfrågan. Dessa element understödjer en florerandestadskärneutveckling men också god krishantering. / As a result of the covid-19 pandemic, many cities have been hit by large turnover losses in business. Themunicipality and the businesses that make up the city center today face major challenges, but alsopotential opportunities. This thesis aims to shed light on how collaborative relationships within urbandevelopment work can act as emergency preparedness in crises as well as what development opportunitiesthe crisis creates. The study is conducted at three city centers with varying degrees of collaboration: Kalmar, Ronneby andVisby. The results pointed overwhelmingly towards that collaboration between the municipality, businessand property owners in the city is perceived as a form of preparedness. It is therefore of utmostimportance to invest in creating good collaboration relationships within the city in good times to createthe conditions for effective crisis management. The study has found that there are certain success factors that are important for a city center to considerin its development. These are the importance of trust between functions and people, establishedcommunication paths and long-term strategic planning for increased demand. These elements support athriving urban development, but also good crisis management.
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Liquidity and yield spreads of corporate bondsTishchenko, Sergei Ivanovich 12 October 2004 (has links)
No description available.
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Rescinding a Bid: Stockholm's uncertain relationship with the Olympic GamesOlson, Erik Johan 23 April 2018 (has links)
The City of Stockholm has undergone a curious process of considering whether to launch a bid for the 2026 Winter Olympic Games. That Stockholm has contemplated launching a bid is not surprising from a regional perspective—the Olympic Games have not been held in a Scandinavian country since Lillehammer, Norway played host in 1994 and Sweden has never hosted the Winter Olympics. A potential bid from Stockholm would also be consistent with Sweden's self-identification and embracement of being a 'sportive nation'. Failed applications by the Swedish cities of Gothenburg, Falun, and Östersund to host the Winter Olympic Games confirm the long-standing interest of the Swedish Olympic Committee to secure the Games, although it should be noted that the Swedish Olympic Committee did not submit a bid for the 2006, 2010, 2014 or 2018 Winter Olympic Games competitions. Although recent reports indicate that Stockholm will not vie for the 2026 Winter Olympic Games, the notion that the city was even considering the option remains surprising. Stockholm had withdrawn its bid from the 2022 bidding competition citing a variety of concerns including a lack of government and public support, financial uncertainty, as well as the post-event viability of purpose-built infrastructure. Stockholm's withdrawal from the 2022 competition resonates with the growing apprehension by potential bid cities (especially those emerging from democratic countries) towards the Olympic Games. This thesis seeks to illustrate that Stockholm's Olympic hopes have book-ended a transformative period in the Olympic bidding process and to expose the struggle that bid cities have in adjusting to the demands of the IOC's bidding process. / Master of Science
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Anticipating a bid/no-bid decision model for an ICT service companyEmmerich, Franck January 2017 (has links)
This report analyses and describes how the bid/no-bid decisions are made at one ICT service company. The analysis is based on current available research within the area of multi criteria decision analysis to enhance the company’s decision process. It proposes how the bid engagement decision can be structured and evaluated. Through a questionnaire at the ICT company, data from its own bids was collected to identify the factors perceived to be relevant to the bid/no bid decision. It is found that the factors can vary depending on industry, market and potentially bid situation, requiring experts’ assessment of which factors to use for each bid situation. Concluding the study, an initial bid model is proposed, but with reservations due to lack of validation in real life situations. A recommendation to expand the existing bid model with probability distribution based risk estimates is made.
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O projeto e a encomenda pública da arquitetura : lex versus publica architecturaeSilva, Tiago Holzmann da January 2018 (has links)
A falta de qualidade das obras públicas no Brasil povoa os noticiários diários. Os exemplos são abundantes, atribuídos a contratos mal elaborados, falhas graves nos projetos ou mesmo à ausência desses, licitações frustradas, obras interrompidas e superfaturadas, desvios de recursos e corrupção. Tentar compreender melhor essa situação é a motivação desta dissertação, que discorre sobre a contratação pública de projetos de edificações e, para isso, estuda o projeto e sua encomenda. A licitação é um procedimento obrigatório para a celebração de qualquer contrato público. Entre outros requisitos, a lei de licitações exige que a proposta seja a “mais vantajosa” para a administração, algo que tem levado à adoção indiscriminada do critério do “menor preço”, sendo incoerente com a doutrina jurídica e contrariando as pesquisas científicas, que consideram o projeto relevante para a qualidade final da obra. O problema de pesquisa questiona exatamente por que a Administração Pública tem contratado por menor preço um serviço que deveria ser contratado por critérios técnicos e de qualidade? O objetivo da dissertação é propor uma explicação para essa situação a partir de revisão bibliográfica, análise da legislação, realização de pesquisa documental com editais de licitação, aplicação de questionários de opinião com arquitetos e outros atores, além de entrevista direta com o autor da lei de licitações. Finalmente, o trabalho comprova a relevância do projeto, mas também desvenda sua irrelevância identificando que o menor preço não é o único problema e, mesmo que “todos” afirmem ser contra o menor preço, o povo segue pagando caro por projetos baratos. / The qualityless of public works in Brazil is currently in the daily news. Examples of it are plentiful, attributed to poorly drafted contracts, serious failures or even absence of projects, frustrated bids, discontinued and overpriced works, waste of resources and corruption. The motivation of this dissertation is trying to better understand this situation, which focuses on the public contracting of building projects and, for this, studies the project itself and its order. Bidding is a mandatory procedure for obtaining any public contract. Among other requirements, the bidding law requires that the proposal be the "most advantageous" for the administration, which ledded to the indiscriminate adoption of the "lowest price" criteria, incoerent with the juridical doctrine and opposite to scientific research, which consider the project relevant to the final quality of the building work. The research problem questions why the Public Administration has contracted for a lower price a service that should be contracted by technical and quality criteria? The objective of the dissertation is to propose an explanation for this situation from a bibliographical review, an analysis of the legislation, a documental research on bid’s documents, an opinion questionaries applying to architects and other actors, as well as direct interview with the author of the bidding law. Finally, the research proves the relevance of the project, but also reveals its irrelevance by identifying that the lowest price is not the only problem, and even if "everyone" claims to be against the lowest price, people continue to pay expensive for cheap projects.
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Bancos multilaterais de desenvolvimento e capacidade estatal : o BID, o Brasil e a ArgentinaMakino, Rogério 14 April 2015 (has links)
Tese (doutorado)—Universidade de Brasília, Instituto de Ciências Sociais, Centro de Pesquisa e Pós-Graduação sobre as Américas, 2015. / Na perspectiva institucionalista, a capacidade estatal é, cada vez mais, reconhecida como um requisito necessário, mas insuficiente, para o desenvolvimento. Agências de desenvolvimento, como bancos multilaterais de desenvolvimento, também têm como objetivo a promoção do desenvolvimento. No entanto, praticamente não há estudos sobre a relação entre bancos multilaterais de desenvolvimento e capacidade estatal. Analisa-se a relação entre os programas de Modernização de Estado do Banco Interamericano de Desenvolvimento e os elementos básicos constituintes da capacidade estatal (capacidade tributária-arrecadatória e quadro burocrático-administrativo qualificado) de Brasil e Argentina em um período em que se tornou imperativo reformar o Estado - o da ascensão das ideias neoliberais na América Latina –, recortado temporalmente entre os anos de 1990 e 2002. Metodologicamente, essa tese estrutura-se por uma estratégia comparativa em torno das relações BID-Brasil e BID-Argentina. A dependência da trajetória, a preocupação com a autonomia nacional e a convergência em torno dos princípios que estruturam os programas são fatores que interferem quantitativa e qualitativamente nas parcerias firmadas entre bancos e prestatários e, consequentemente, no potencial de transformação da capacidade estatal. Nesse sentido, os casos estudados sugerem que o papel dos bancos multilaterais de desenvolvimento é limitado e, mesmo quando o prestatário está extremamente comprometido com as reformas, não significa necessariamente aumento da capacidade estatal. Esses programas têm o potencial de magnificar os resultados, mas isso pode ocorrer positiva ou negativamente. / In institutionalist perspective, state capacity is increasingly recognized as a necessary, but insufficient requirement for development. Development agencies, such as multilateral development banks, also aim at promoting development. However, there are virtually no studies on the relation between multilateral development banks and state capacity. The analysis concerns the relations between the Inter-American Development Bank’s programs of State Modernization and the constituent basic elements of state capacity (tax collection capacity and qualified bureaucratic-administrative staff) of Brazil and Argentina in a time when everyone believed it was necessary to reform the state - the rise of neoliberal ideas in Latin America - specifically between the years 1990 and 2002. Methodologically, this dissertation is structured by a comparative strategy around the IDB-Brazil and IDB-Argentina relations. Path dependency, concern for national autonomy and convergence (self-conviction) around the principles underlying the programs are factors that affect the quantity and quality of the partnerships between banks and borrowers and hence the potential for transformation of state capacity. In this sense, the studied cases suggest that the role of multilateral development banks is limited and, even when the borrower is extremely committed to the reforms, it does not necessarily mean increased state capacity. These programs have the potential to magnify the results, but this may be positively or negatively. / En perspectiva institucionalista, la capacidad estatal es cada vez más reconocida como un requisito necesario, pero no suficiente para el desarrollo. Las agencias de desarrollo, incluso los bancos multilaterales de desarrollo, también tienen por objeto promover el desarrollo. Sin embargo, prácticamente no hay estudios sobre la relación entre los bancos multilaterales de desarrollo y la capacidad estatal. En esta tesis se analiza la relación entre los programas de la Modernización del Estado del Banco Interamericano de Desarrollo y los elementos básicos constitutivos de la capacidad del Estado (la capacidad de recaudación de impuestos y el cuadro burocrático-administrativo calificado) de Brasil y Argentina en un período en el que se entendía como mprescindible la reforma del Estado - el auge de las ideas neoliberales en América Latina – especialmente entre los años 1990 y 2002. Em término metodológicos, esta tesis se estrucutura mediante una estrategia comparativa de las relaciones BID-Brasil y BID-Argentina. La dependencia de la trayectoria, la preocupación por la autonomía nacional y la convergencia (autoconvicción) en torno a los principios que subyacen a los programas, son factores que afectan la cantidad y la calidad de las asociaciones entre los bancos y los prestatarios y, por tanto, el potencial para la transformación de la capacidad estatal. Sin embargo, se destaca que los casos estudados sugieren que el rol de los bancos multilaterales de desarrollo tiene importancia secundaria, aun cuando el prestatario es extremadamente comprometido con las reformas. En este sentido, los casos investigados sugieren que el rol de los bancos multilaterales de desarrollo es limitado y, aun cuando el prestatario es extremadamente comprometido con las reformas, no significa necesariamente el aumento de la capacidad del Estado. Estos programas tienen el potencial para ampliar los resultados, pero esto puede suceder positiva o negativamente.
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The intraday pattern of information asymmetry : evidence from the NYSEWang, Juan 11 September 2009
Previous studies (e.g. Benston and Hagerman, 1974, Bagehot, 1971 and Stoll, 1978) suggest that the bid-ask spread consists of three components: asymmetric information cost, inventory holding cost, and order processing cost. Other literature (e.g. Brock and Kleidon, 1992, Hef-lin et al, 2007, and McInish and Van Ness, 2002) reports that the bid-ask spread varies during a trading day following a U-shaped pattern. One explanation for this observation is that it is the result of changes in information asymmetry costs over the trading hours, assuming the other costs are fixed. However, no empirical study directly measures how information asym-metry changes over the trading day. We explore how this measure relates to the spread as well as the quote depth.<p>
Our research divides a trading day into 13 half-hour trading intervals and measures in-formation asymmetry during each interval following the model developed by Madhavan and Smidt (1991) and Noronha et al (1996). Their model can directly estimate the level of infor-mation asymmetry in each interval. This enables us to observe the intraday pattern of infor-mation asymmetry directly and compare it to the patterns of the spread and the quote depth. Furthermore, we test the relationship between the spread and the information asymmetry and the relationship between the depth and the information asymmetry in a dynamic context to see how market makers manage information risk over trading hours.<p>
We find that the risk of information asymmetry varies significantly during the trading day. There is a large drop over the first interval, and another large drop over the last interval, with smaller fluctuations over the remaining intervals. Moreover, we show that the spread is consistent with an L-shaped pattern as opposed to the U-shaped pattern proposed by previous studies while the depth is increasing throughout the 13 trading intervals. Furthermore, we ob-serve that the variations of the spread and the depth are respectively positively and negatively related to the intraday variations in the degree of information asymmetry across the trading intervals. In particular, a large decline in information asymmetry at the beginning of the day is associated with a large reduction in the spread, whereas a large decline in information asymmetry at the end of the day is associated with a large increase in the quote depth. This emphasises the importance of studying both measures of liquidity simultaneously.
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Short - Term Bidding Strategies for a Generation Company in the Iberian Electricity MarketCorchero García, Cristina 02 February 2011 (has links)
La posada en marxa del Mercat Ibèric de l'Electricitat va introduir al sector elèctric espanyol un seguit de nous mecanismes de participació que han forçat els agents a renovar les seves polítiques de gestió. D'aquesta nova situació sorgeix l'oportunitat d'estudiar noves estratègies d'oferta a curt termini per a companyies de generació price-taker que participin diàriament al Mercat Ibèric de l'Electricitat. Aquestes estratègies se centraran al mercat diari, ja que és aquí on es negocia un 80% de l'electricitat que es consumeix diàriament a Espanya i on s'integren gran part de la resta de mecanismes de participació. La liberalització dels mercats elèctrics obre a noves tècniques d'optimització els problemes clàssics de gestió de l'energia. En particular, atesa la incertesa que l'existència del mercat ocasiona als preus, les tècniques de programació estocàstiques es converteixen en la forma més natural per abordar aquests problemes. Als mercats elèctrics el preu es fixa horàriament com a resultat d'un procés de casació , és a dir que quan l'agent ha d'efectuar la seva oferta desconeix el preu al qual li vindrà remunerada l'energia. Aquesta incertesa fa imprescindible l'ús de tècniques estadístiques per obtenir informació del mercat i introduir-la als models d'optimització. En aquest aspecte, una de les contribucions d'aquesta tesi és l'estudi dels preus del mercat de l'electricitat a Espanya i el seu modelat mitjançant models factorials. D'altra banda, s'hi es descriuen els nous mecanismes presents al Mercat Ibèric de l'Electricitat que afecten directament la producció física de les unitats. En particular, s'inclou el modelat detallat dels contractes de futurs físics i bilaterals i de la seva inclusió a l'oferta del mercat diari per part de les companyies de generació. Als models presentats, es tenen en compte explícitament les regles del mercat, així com les clàssiques restriccions d'operació de les unitats, tant tèrmiques com de cicle combinat. A més, es deriva i es demostra l'expressió de la funció d'oferta. Per tant, els models construïts són una eina per decidir l'assignació de les unitats, la generació dels contractes de futurs físics i bilaterals a través seu i l'oferta òptima d'una companyia de generació. Un cop s'han cobert aquests objectius, es presenta una millora dels models mitjançant la inclusió de la seqüència de mercats de molt curt termini per tal de modelar la influència que tenen en l'oferta al mercat diari. Aquests mercats es casen just abans i durant el dia en què l'energia ha de ser consumida, i això permetrà veure com la possibilitat d'augmentar els beneficis participant-hi afecta directament les estratègies d'oferta òptima del mercat diari. Els models presentats en aquest treball han estat provats amb dades reals provinents del Mercat Ibèric de l'Electricitat i d'una companyia de generació que hi opera. Els resultats obtinguts són adequats i es discuteixen al llarg del document / La puesta en marcha del Mercado Ibérico de la Electricidad introdujo en el sector eléctrico español una serie de nuevos mecanismos de participación que han forzado a los agentes a renovar sus políticas de gestión. De esta nueva situación surge la oportunidad de estudiar nuevas estrategias de oferta para las compañías de generación. Esta tesis se enmarca en las estrategias de oferta a corto plazo para compañías de generación price-taker que participen diariamente en el Mercado Ibérico de la Electricidad. Estas estrategias se centraran en el mercado diario ya que es donde se negocia un 80% de la electricidad consumida diariamente en España y es donde se integran gran parte del resto de los mecanismos de participación. La liberalización de los mercados eléctricos permite aplicar nuevas técnicas de optimización a los problemas clásicos de gestión de la energía. En concreto, dada la incertidumbre en el precio existente en el mercado, las técnicas de programación estocástica se convierten en la forma más natural para abordar estos problemas. En los mercados eléctricos el precio se fija horariamente como resultado de un proceso de casación, es decir, cuando el agente debe efectuar sus ofertas desconoce el precio al que la energía le será pagada. Esta incertidumbre hace imprescindible el uso de técnicas estadísticas para obtener información del mercado e introducirla en los modelos de optimización. En este aspecto, una de las contribuciones de esta tesis es el estudio del precio de la electricidad en España y su modelado mediante modelos factoriales. Se describen los nuevos mecanismos presentes en el Mercado Ibérico de la Electricidad que afectan directamente a la producción física de las unidades. En particular, se incluye una modelización detallada de los contratos de futuros físicos y bilaterales y su inclusión en la oferta enviada al mercado diario por las compañías de generación. En los modelos presentados se tiene en cuenta explícitamente las reglas del mercado así como las clásicas restricciones de operación de las unidades, tanto térmicas como de ciclo combinado. La expresión de la función de oferta óptima se deriva y se demuestra. Por lo tanto, los modelos construidos son una herramienta para decidir la asignación de unidades, la generación de los contratos de futuros físicos y bilaterales a través de ellas y la oferta óptima de una compañía de generación. Una vez alcanzados estos objetivos, se presenta una mejora del modelo con la inclusión de la secuencia de mercados de muy corto plazo. El objetivo es modelar la influencia que esta tiene en la oferta al mercado diario. Estos mercados se casan justo antes y durante el día en el que la energía va a ser consumida y se verá cómo la posibilidad de aumentar los beneficios participando en ellos afecta a las estrategias de oferta óptima del mercado diario. Los modelos presentados en este trabajo se han probado con datos reales procedentes del Mercado Ibérico de la Electricidad y de una compañía de generación que opera en él. Los resultados obtenidos son adecuados y se discuten a lo largo del documento. / The start-up of the Iberian Electricity Market introduced a set of new mechanisms in the Spanish electricity sector that forced the agents participating in the market to change their management policies. This situation created a great opportunity for studying the bidding strategies of the generation companies in this new framework. This thesis focuses on the short-term bidding strategies of a price-taker generation company that bids daily in the Iberian Electricity Market. We will center our bidding strategies on the day-ahead market because 80% of the electricity that is consumed daily in Spain is negotiated there and also because it is the market where the new mechanisms are integrated. The liberalization of the electricity markets opens the classical problems of energy management to new optimization approaches. Specifically, because of the uncertainty that the market produces in the prices, the stochastic programming techniques have become the most natural way to deal with these problems. Notice that, in deregulated electricity markets the price is hourly fixed through a market clearing procedure, so when the agent must bid its energy it is unaware of the price at which it will be paid. This uncertainty makes it essential to use some statistic techniques in order to obtain the information coming from the markets and to introduce it in the optimization models in a suitable way. In this aspect, one of the main contributions of this thesis has been the study the Spanish electricity price time series and its modeling by means of factor models. In this thesis, the new mechanism introduced by the Iberian Market that affects the physical operation of the units is described. In particular, it considers in great detail the inclusion of the physical futures contracts and the bilateral contracts into the day-ahead market bid of the generation companies. The rules of the market operator have been explicitly taken into account within the mathematical models, along with all the classical operational constraints that affect the thermal and combined cycle units. The expression of the optimal bidding functions are derived and proved. Therefore, the models built in this thesis provide the generation company with the economic dispatch of the committed futures and bilateral contracts, the unit commitment of the units and the optimal bidding strategies for the generation company. Once these main objectives were fulfilled, we improved the previous models with an approach to the modeling of the influence that the sequence of very short markets have on optimal day-ahead bidding. These markets are cleared just before and during the day in which the electricity will be consumed and the opportunity to obtain benefits from them changes the optimal day-ahead bidding strategies of the generation company, as it will be shown in this thesis. The entire models presented in this work have been tested using real data from a generation company and Spanish electricity prices. Suitable results have been obtained and discussed.
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Representations and Parameterizations of Combinatorial AuctionsLoker, David Ryan January 2007 (has links)
Combinatorial auctions (CAs) are an important mechanism for allocating multiple items while allowing agents to specify preferences over bundles of items. In order to communicate these preferences, agents submit bids, which consist of one or more items and a value indicating the agent’s preference for these items. The process of determining the allocation of items is known as the winner determination problem (WDP). WDP for CAs is known to be NP-complete in the general case.
We consider two distinct graph representations of a CA; the bid graph and the item graph. In a bid graph, vertices represent bids, and two vertices are adjacent if and only if the bids share items in common. In an item graph, each vertex represents a unique item, there is a vertex for each item, and any bid submitted by any agent must induce a connected subgraph of the item graph. We introduce a new definition of combinatorial
auction equivalence by declaring two CAs equivalent if and only if their bid graphs are isomorphic.
Parameterized complexity theory can be used to further distinguish between NP-hard
problems. In order to make use of parameterized complexity theory in the investigation of a problem, we aim to find one or more parameters that describe some aspect of the problem such that if we fix these parameters, then either the problem is still hard (fixed-parameter intractable), or the problem can be solved in polynomial time (fixed-parameter tractable).
We analyze WDP using bid graphs from within the formal scope of parameterized complexity theory. This approach has not previously been used to analyze WDP for CAs, although it has been used to solve set packing, which is related to WDP for CAs and is discussed in detail. We investigate a few parameterizations of WDP; some of the parameterizations are shown to be fixed-parameter intractable, while others are fixed-parameter tractable. We also analyze WDP when the graph class of a bid graph is restricted.
We also discuss relationships between item graphs and bid graphs. Although both graphs can represent the same problem, there is little previous work analyzing direct relationships between them. Our discussion on these relationships begins with a result by
Conitzer et al. [7], which focuses on the item graph representation and its treewidth, a property of a graph that measures how close the graph is to a tree. From a result by Gavril, if an item graph has treewidth one, then the bid graph must be chordal [16]. To apply the other direction of Gavril’s theorem, we use our new definition of CA equivalence. With this new definition, Gavril’s result shows that if a bid graph of a CA is chordal, then we can construct an item graph that has treewidth one for some equivalent CA.
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Representations and Parameterizations of Combinatorial AuctionsLoker, David Ryan January 2007 (has links)
Combinatorial auctions (CAs) are an important mechanism for allocating multiple items while allowing agents to specify preferences over bundles of items. In order to communicate these preferences, agents submit bids, which consist of one or more items and a value indicating the agent’s preference for these items. The process of determining the allocation of items is known as the winner determination problem (WDP). WDP for CAs is known to be NP-complete in the general case.
We consider two distinct graph representations of a CA; the bid graph and the item graph. In a bid graph, vertices represent bids, and two vertices are adjacent if and only if the bids share items in common. In an item graph, each vertex represents a unique item, there is a vertex for each item, and any bid submitted by any agent must induce a connected subgraph of the item graph. We introduce a new definition of combinatorial
auction equivalence by declaring two CAs equivalent if and only if their bid graphs are isomorphic.
Parameterized complexity theory can be used to further distinguish between NP-hard
problems. In order to make use of parameterized complexity theory in the investigation of a problem, we aim to find one or more parameters that describe some aspect of the problem such that if we fix these parameters, then either the problem is still hard (fixed-parameter intractable), or the problem can be solved in polynomial time (fixed-parameter tractable).
We analyze WDP using bid graphs from within the formal scope of parameterized complexity theory. This approach has not previously been used to analyze WDP for CAs, although it has been used to solve set packing, which is related to WDP for CAs and is discussed in detail. We investigate a few parameterizations of WDP; some of the parameterizations are shown to be fixed-parameter intractable, while others are fixed-parameter tractable. We also analyze WDP when the graph class of a bid graph is restricted.
We also discuss relationships between item graphs and bid graphs. Although both graphs can represent the same problem, there is little previous work analyzing direct relationships between them. Our discussion on these relationships begins with a result by
Conitzer et al. [7], which focuses on the item graph representation and its treewidth, a property of a graph that measures how close the graph is to a tree. From a result by Gavril, if an item graph has treewidth one, then the bid graph must be chordal [16]. To apply the other direction of Gavril’s theorem, we use our new definition of CA equivalence. With this new definition, Gavril’s result shows that if a bid graph of a CA is chordal, then we can construct an item graph that has treewidth one for some equivalent CA.
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