Affliation in Multi-Unit Auctions

We extend Milgrom and Weber’s affiliated valuations model to the multi-unit case with constant marginal valuations where 2 bidders compete for k identical objects. We show that the discriminatory auction has a unique equilibrium, that corresponds to Milgrom and Weber’s firstprice equilibrium. This unique equilibrium therefore leads to lower expected prices than the equilibrium of the English auction where the units are bundled together. Hence we show that in a common value auction of a single object where the object can be divided into k parts, it is not possible to increase revenue by using a multi-unit discriminatory auction. We discuss a possible application to Treasury auctions.Affiliated Valuations, Multi-Unit Auctions, Treasury Auctions.

On the Co-Existence of Conventions

Recent stochastic evolutionary models have shown that the most likely convention when the probability of a mutation is sufficiently small is coordination on the risk-dominant strategy rather than the payoff-dominant one. This paper looks at the consequences of player movement between locations when there are constraints which limit the number of agents who can reside at each location. If the constraints are strong then the risk-dominance result continues to hold. However, we show that when sufficient movement is possible, the most likely outcome involves a mixed state in which agents at different locations coordinate on different strategies. In the asymmetric case, it is the location with the stronger constraint, limiting movement, that coordinates on the payoff-dominant strategy.Evolution, Local Interaction, Equilibrium Selection

Single or Multiple Pricing in Electricity Pools?

We present a 2 bidder multi-unit, common cost auction model with uncertain demand and capacity constraints which ensure that the participants sometimes face a residual market share. The model is motivated by electricity pools. We show that a single-price auction where the bidders can submit only one bid for all units weakly dominates an auction where the bidders can make multiple-price bids in terms of average prices. In the case of uniform price auctions we give an example where the dominance is strict.Electricity Pool, Multi-Unit Auction, Revenue Ranking

The Apple Tree

Consider an individual whose preferences are changing over time. How do we assess her welfare? We argue that this is an empirically relevant question as preferences are constantly changing over time if the agent has a bias towards the present. We present a simple example where preferences are changing over time (the apple tree) and use it to aid our discussion of welfare. We critically assess the approach that focuses on the decision maker (revealed preference) and the one that ignores the decision maker (long-run self) with reference to some recent literature. Finally, we look at some of the problems that arise when we consider a sovereign individual who aggregates her changing preferences.

Assessing the current status of the newly revised plasma television program instruction: the case of Silte zone secondary schools

The main objective of this study is to assess the current status of the newly revised plasma television program instruction (PTVPI) in Silte Zone secondary schools. Hence, it tried to examine the extent to which classroom teachers and students perform their roles as stated in plasma guide. In addition to this, it tried to examine the extent to which principals support PTVPI, strengths of the newly revised PTVP and factors affecting it. To accomplish this purpose, the study employed descriptive research design. The study was carried out on 6 secondary schools which were selected through the combination of both available and simple random sampling techniques. Then, a total of 304 individuals participated in the study. Among them, 130 teachers and 6 supervisors were included in the sample through available sampling technique. Additionally, 156 students were included through stratified random sampling while the remaining 12 principals were included through the combination of both purposive and available sampling techniques. Questionnaire, interview and observation checklist were used to collect the necessary data regarding the issue. The analysis of the quantitative data was carried out by using percent, mean, standard deviation, independent sample t-test and one-way ANOVA while qualitative data which were obtained through open ended questions and interview were analyzed using narration. The result of the study revealed that, both classroom teachers and principals are sometimes (moderately) performing their roles while students are usually performing their roles. Moreover, the study found out that, the strengths of the newly revised PTVP are highly supporting both the teachers and students to perform their roles while shortage of new PTVs that take CDs and lack of DVDs in schools are extremely affecting PTVPI among many factors in the study area. From the results of the finding, it is possible to conclude that, status of PTVPI in the study area is moderate. Based on the findings of the study, it is recommended that, government need to provide material support to schools and technical support to both teachers and principals through training in order to improve status of PTVPI in the study area by participating the community as well as non-governmental organizations (NGOs).Jimma Universit

Interference-Based Optimal Power-Efficient Access Scheme for Cognitive Radio Networks

In this paper, we propose a new optimization-based access strategy of multipacket reception (MPR) channel for multiple secondary users (SUs) accessing the primary user (PU) spectrum opportunistically. We devise an analytical model that realizes the multipacket access strategy of SUs that maximizes the throughput of individual backlogged SUs subject to queue stability of the PU. All the network receiving nodes have MPR capability. We aim at maximizing the throughput of the individual SUs such that the PU's queue is maintained stable. Moreover, we are interested in providing an energy-efficient cognitive scheme. Therefore, we include energy constraints on the PU and SU average transmitted energy to the optimization problem. Each SU accesses the medium with certain probability that depends on the PU's activity, i.e., active or inactive. The numerical results show the advantage in terms of SU throughput of the proposed scheme over the conventional access scheme, where the SUs access the channel randomly with fixed power when the PU is sensed to be idle

Effective Capacity of Cognitive Radio Links: Accessing Primary Feedback Erroneously

We study the performance of a cognitive system modeled by one secondary and one primary link and operating under statistical quality of service (QoS) delay constraints. We analyze the effective capacity (EC) to quantify the secondary user (SU) performance under delay constraints. The SU intends to maximize the benefit of the feedback messages on the primary link to reduce SU interference for primary user (PU) and makes opportunistic use of the channel to transmit his packets. We assume that SU has erroneous access to feedback information of PU. We propose a three power level scheme and study the tradeoff between degradation in EC of SU and reliability of PU defined as the success rate of the transmitted packets. Our analysis shows that increase in error in feedback access causes more interference to PU and packet success rate decreases correspondingly.Comment: Accepted for publication in International Symposium on Wireless Communication Systems (ISWCS) 201