The Value of Commitment in Auctions with Matching

In many auctions, a good match between the bidder and seller raises the value of the contract for both parties although information about the quality of the match may be incomplete. This paper examines the case in which the bidder is better informed about the quality of his match with the seller than the seller is. We derive the optimal mechanism for this setting and investigate whether the seller requires commitment power to implement it. It is shown that once the reserve price is set, it is optimal for the seller to do away with any matching considerations and allocate the contract on the basis of price alone. If matching is sufficiently important to the seller, the optimal mechanism may be implemented without commitment. However, if matching is not sufficiently important, the seller suffers a loss when he is unable to commit. The magnitude of this loss increases as the importance of matching decreases.Asymmetries, Auctions, Auction Theory, Bidding, Matching, Mechanism Design, Signaling

Ignorance Is Bliss: Matching in Auctions with an Uninformed Seller

In many auctions, matching between the bidder and seller raises the value of the contract for both parties. However, information about the quality of the match may be incomplete. We consider the case in which each bidder observes the quality of his match with the seller but the seller does not observe the quality of his matches with the bidders. Our objective is to determine whether it is in the seller's interest to observe the matches before selecting the winner. It is shown that the seller’s value for the information may be negative: the seller’s knowledge of the matches generates an asymmetry across bidders which depresses bids. The more matching matters, the greater the penalty associated with observing the matches.Asymmetries, Auctions, Auction Theory, Bidding, Information Revelation, Matching, Signaling

Linear Logic for Meaning Assembly

Semantic theories of natural language associate meanings with utterances by providing meanings for lexical items and rules for determining the meaning of larger units given the meanings of their parts. Meanings are often assumed to combine via function application, which works well when constituent structure trees are used to guide semantic composition. However, we believe that the functional structure of Lexical-Functional Grammar is best used to provide the syntactic information necessary for constraining derivations of meaning in a cross-linguistically uniform format. It has been difficult, however, to reconcile this approach with the combination of meanings by function application. In contrast to compositional approaches, we present a deductive approach to assembling meanings, based on reasoning with constraints, which meshes well with the unordered nature of information in the functional structure. Our use of linear logic as a `glue' for assembling meanings allows for a coherent treatment of the LFG requirements of completeness and coherence as well as of modification and quantification.Comment: 19 pages, uses lingmacros.sty, fullname.sty, tree-dvips.sty, latexsym.sty, requires the new version of Late

Remediation Strategies and Water Quality of estuarine impoundments

The implementation of amenity barrage schemes, such as the recent projects on the Tees Barrage and at Cardiff Bay, has gained popularity as part of urban regeneration projects in the UK. The predecessors of these schemes on the rivers Tawe, Lagan and Wansbeck offer valuable information on the impacts and remediation strategies that maybe required to sustain good water quality in the newly created upstream impoundment. Depending on the design, the stored water body is affected by: density stratification; flow velocity reduction; siltation and contaminant accumulation; all of which can lead to periods of poor water quality following barrage construction. This thesis identifies the principle dynamics leading to low water quality within a partial exclusion system (River Tawe) through numerical and observational analysis of monitoring data recorded over the last nine years. Temporal variation of water quality within total exclusion system (Tees Barrage) is described from continuous monitoring records covering a three-year period. The data for both designs showed significant seasonal variation and flow was identified as a major factor in the process of low water quality development. In addition, the influence of the tidal regime was determined for the oxygen and salinity dynamics in the partial exclusion impoundment. Due to influx of saline water, partial exclusion systems are likely to suffer from saline stratification, which restricts the mixing processes in the water column and often leads to DO depletion in the lower layers of the impoundment. Several remediation strategies have been applied and proposed to prevent this process, including measures to break-up (Mixers), to prevent (Baffles) or to flush out (Sluicing) the stratified water body. Each of these principles is presented and discussed in this work separately, to determine its feasibility for the future management of water quality in partial exclusion impoundments. The installation of a mixing system in the Tawe impoundment was proved to be successful in breaking up saline stratification and recommendations are given for further adjustment. Flushing was ruled out as an effective measure to improve water quality due to its inability to completely expel low dissolved oxygen water. A future installation involving a floating boom/skirt system was tested in laboratory experiments and the general feasibility of concept was confirmed, whilst design criteria for the prototype were established

Dusty Windows and urban American dreams: Five African journeys toward literacy through participatory research and program development

When we talk about education, rarely do the faces of this research enter our minds. English as a Second Language (ESL) programs all over the United States, however, are familiar with these new faces. Over the past fifteen years, schools have begun to see a dramatic increase in the number of ESL students whose educations have either never been formal or have been disrupted by wars and socioeconomic issues in their home countries. Among this newer group of students are an increasing number of adult (high school and beyond) African immigrants who come from ethnic groups in which language and literacy have always been oral experiences. As a result, programs are consistently struggling to accommodate them in a country and culture that depends heavily on the printed word. Thus, classrooms and programs must seek new ways to educate them as they learn to read and write in English, without any written literacy in their native languages. This study was a collaborative effort with five African men from oral language backgrounds. It was an investigation into their journeys to read, write, and manage their own cultural transitions in urban America. The study found that their success in this journey relied heavily on the profound role participatory schooling has had in their lives