Set Of Sellers Research Articles

A multi-agent coalition-based approach for order fulfilment in e-commerce

The rapid growth of e-commerce in the recent pandemic is driven by the wide adoption of digitization, extensive use of smartphones, affordable internet services, and the convenience of shopping from anywhere and anytime. Some key indexes for measuring the performance of the e-commerce organization include affordable deals, competitive prices, and efficiency in fulfilling orders while ensuring customer satisfaction. Customer review ratings are one of the significant metrics to measure customer satisfaction, influencing other customers to make purchase decisions. Therefore, favourable customer reviews and ratings of various products presented on e-commerce platforms provide competitive advantages to sellers. Usually, customers placing an order on an e-commerce platform are notified about the estimated delivery date. Consequently, after receiving the product delivery, customers give feedback in the form of review comments and ratings to communicate their satisfaction or dissatisfaction towards the seller. In case of delays in order fulfilment, the customers mostly give negative feedback along with poor ratings, which can affect the seller’s reputation, thus impacting future sales. Therefore, the central idea of this research is to adopt a resilient order fulfilment approach by identifying the optimal set of sellers based on fulfilment cost, lead time for fulfilment and review rating score obtained from previous orders. The research work has been divided into three different phases. Firstly, significant constraints associated with an e-commerce fulfilment system have been identified from existing literature. The relationship between the lead time in order fulfilment and review rating score is studied. Finally, a multi-agent coalition-based framework is proposed for generating the Pareto-optimal set of reliable sellers to fulfil an order. Although sellers in an e-commerce marketplace are usually considered competitors of each other, a temporary coalition among the sellers for aggregated order fulfilment can minimize fulfilment costs. The proposed multi-agent coalition-based framework is implemented on real-time data to confirm the findings.

Minimizing settlements

A set of sellers have to ship certain quantities of a homogeneous good to a set of buyers. The objective is to minimize the number of shipments when the shipping costs only depend on the number of shipments. We provide an upper bound on the minimum number of settlements, but we show that knowing whether the minimum number of settlements can be lower for a given problem is an NP-complete problem.

On Distinguishing Between Valuation and Arbitrage Motivated Short Selling

The short interest data reported in the United States aggregate valuation shorts (motivated by a pessimistic opinion on firm value) and arbitrage shorts (motivated by various arbitrage or hedging strategies). However, the information content of these two sources of short interest is different and hence their association with future returns is expected to be different. In recent years, the association between short interest and future returns has weakened considerably, reflecting the increasing importance of institutions that execute arbitrage strategies. The primary contribution of this study is an empirical model that ex-ante helps differentiate valuation shorts from arbitrage shorts. In out-of-sample tests, we document that, consistent with theoretical predictions, the firms identified by the model as valuation shorts exhibit high short interest and poor future returns. Furthermore, firms identified as arbitrage shorts do not exhibit significant negative returns but instead exhibit characteristics associated with arbitrage strategies. The paper also identifies variables that are correlated with the information set of short sellers. We present an application that exploits the model's ability to ex-ante identify poor performers and discuss broader applications in other finance settings.

Bargaining Frictions in Trading Networks

AbstractIn the canonical model of frictionless markets, arbitrage is usually taken to force all trades of homogeneous goods to occur at essentially the same price. In the real world, however, arbitrage possibilities are often severely restricted and this may lead to substantial price heterogeneity. Here we focus on frictions that can be modeled as the bargaining constraints induced by an incomplete trading network. In this context, the interplay among the architecture of the trading network, the buyers’ valuations, and the sellers’ costs shapes the effective arbitrage possibilities of the economy. We characterize the configurations that, at an intertemporal bargaining equilibrium, lead to a uniform price. Conceptually, this characterization involves studying how the network positions and valuations/costs of any given set of buyers and sellers affect their collective bargaining power relative to a notional or benchmark situation in which the connectivity is complete. Mathematically, the characterizing conditions can be understood as price-based counterparts of those identified by the celebrated Marriage Theorem in matching theory.

A comprehensive spectrum trading scheme based on market competition, reputation and buyer specific requirements

In the exclusive-use model of spectrum trading, cognitive radio devices or secondary users can buy spectrum resources from licensed users or primary users for a short or long period of time. Considering such spectrum access, a trading model is introduced where a buyer can select a set of candidate sellers based on their reputation and their offers in fulfilling its requirements, namely, offered signal quality, contract duration, coverage and bandwidth. Similarly, a seller can assess a buyer as a potential trading partner considering the buyer’s reliability, which the seller can derive from the buyer’s reputation and financial profile. In our scheme, seller reputation or buyer reliability can be either obtained from a reputation brokerage service, if one exists, or calculated using our model. Since in a competitive market, the price of a seller depends on that of other sellers, game theory is used to model the competition among multiple sellers. An optimization technique is used by a buyer to select the best seller(s) and optimize purchase to maximize its utility. This may result in buying from multiple sellers of certain amount of bandwidth from each, depending on price and meeting requirements and budget constraints. Stability of the model is analyzed and performance evaluation shows that it benefits sellers and buyers in terms of profit and throughput, respectively.

Matching with Frictions and Entry with Poisson Distributed Buyers and Sellers.

I consider a directed search model with population uncertainty. Buyers and sellers are randomly drawn from independent Poisson distributions. This provides a simple justification for the usual equilibrium selection where only symmetric randomizations by buyers are considered, because any equilibrium is payoff equivalent to such symmetric equilibrium. The Poisson assumption also makes the model more tractable, making it possible to handle entry, which is difficult with a fixed finite set of sellers. I also demonstrate that the Poisson model belongs to a more general class of models in which prices are strategic complements. In this class, equilibria are unique if there is a unique symmetric equilibrium.

Generalizing Deferred Acceptance Auctions to Allow Multiple Relinquishment Options

Introduction and the Statement of the Problem. Reallocation of spectrum from current licensees TV broadcasters to mobile uses to promote e cient use of spectrum has become a public policy agenda. The Congress authorized the FCC to conduct incentive auctions for reallocations of spectrum in the UHF band. In this paper, we focus on the design of reverse auctions where TV stations submit bids to voluntarily relinquish spectrum rights to FCC in exchange for payments. The state of the art of the design of reverse auctions is the framework given in Paul Milgrom, Lawrence Ausubel, Jon Levin, and Ilya Segal (2012) and deferred acceptance auctions proposed by Paul Milgrom and Ilya Segal (2014). In deferred acceptance auctions, each seller submits a single o er. At each round, an o er is evaluated with its scoring function. The buyer deletes the o er with the highest score. Then the set of frozen sellers (i.e., the set of sellers who will be assigned back to the band because the scores are too high) will be updated and o ers are re-evaluated. Auctions end when only o ers with the zero score remain. The payment rule is determined by the threshold price that is the maximum amount that the seller can o er to sell. When bidders are single-minded (that is, a bidder can make only one bid), then, the deferred acceptance auctions are strategy-proof, can be implemented in descending clock auctions, nearlyoptimal, group strategy-proofness, and equivalent to payas-bid auctions. But the Spectrum Act 6403(a)(2) stipulates that bidders shall have multiple relinquishment options such as going o the air, moving to the VHF band, and channel sharing. When the seller can make only one o er, the seller has to choose which auction to bid. Then the payment depends on the choice of auctions by other bidders. Therefore, the seller’s choice of auctions can depend on other sellers’ choices. Thus sincere bidding may not be an equilibrium.

On Cobb-Douglas Preferences in Bilateral Oligopoly

SummaryBilateral oligopoly is a simple model of exchange in which a finite set of sellers seek to exchange the goods they are endowed with for money with a finite set of buyers, and no price-taking assumptions are imposed. If trade takes place via a strategic market game bilateral oligopoly can be thought of as two linked proportional-sharing contests: in one the sellers share the aggregate bid from the buyers in proportion to their supply and in the other the buyers share the aggregate supply in proportion to their bids. The analysis can be separated into two “partial games”. First, fix the aggregate bid at B; in the first partial game the sellers contest this fixed prize in proportion to their supply and the aggregate supply in the equilibrium of this game is (B). Next, fix the aggregate supply at X; in the second partial game the buyers contest this fixed prize in proportion to their bids and the aggregate bid in the equilibrium of this game is (X). The analysis of these two partial games takes into account competition within each side of the market. Equilibrium in bilateral oligopoly must take into account competition between sellers and buyers and requires, for example, ((B)) = B. When all traders have Cobb-Douglas preferences (B) does not depend on B and (X) does not depend on X: whilst there is competition within each side of the market there is no strategic interdependence between the sides of the market. The Cobb-Douglas assumption provides a tractable framework in which to explore the features of fully strategic trade but it misses perhaps the most interesting feature of bilateral oligopoly, the implications of which are investigated.

On the use of particle swarm optimization and Kernel density estimator in concurrent negotiations

Electronic Marketplaces (EMs) can offer a number of advantages for users searching for products. In EMs, Intelligent Agents (IAs) can undertake the responsibility of representing buyers and sellers and negotiate over the conclusion of purchases. For this purpose, a negotiation is held between IAs. The most important characteristics are the deadline and the pricing strategy. The strategy defines the proposed prices at every round of the negotiation. We focus on the buyer side. We study concurrent negotiations between a buyer and a set of sellers. In this setting, the buyer utilizes a number of threads. Each thread follows a specific strategy and adopts swarm intelligence techniques for achieving the optimal agreement. The Particle Swarm Optimization (PSO) algorithm is adopted by each thread. Our architecture requires no central coordination. In real situations, there is absolutely no knowledge for the characteristics of the involved entities. In this paper, we model such kind of uncertainty through known techniques for estimating the distribution of deadlines and strategies. One of them is the Kernel Density Estimation (KDE) technique. Our experimental results depict the time interval where the agreement is possible and the efficiency of the proposed model.

The multiple-partners assignment game with heterogeneous sales and multi-unit demands: competitive equilibria

A multiple-partners assignment game with heterogeneous sales and multi-unit demands consists of a set of sellers that own a given number of indivisible units of potentially many different goods and a set of buyers who value those units and want to buy at most an exogenously fixed number of units. We define a competitive equilibrium for this generalized assignment game and prove its existence by using only linear programming. In particular, we show how to compute equilibrium price vectors from the solutions of the dual linear program associated to the primal linear program defined to find optimal assignments. Using only linear programming tools, we also show (i) that the set of competitive equilibria (pairs of price vectors and assignments) has a Cartesian product structure: each equilibrium price vector is part of a competitive equilibrium with all optimal assignments, and vice versa; (ii) that the set of (restricted) equilibrium price vectors has a natural lattice structure; and (iii) how this structure is translated into the set of agents’ utilities that are attainable at equilibrium.

Approximation schemes for deal splitting and covering integer programs with multiplicity constraints

We consider the problem of splitting an order for R goods, R ≥ 1 , among a set of sellers, each having bounded amounts of the goods, so as to minimize the total cost of the deal. In deal splitting with packages (DSP), the sellers offer packages containing combinations of the goods; in deal splitting with price tables (DST), the buyer can generate such combinations using price tables. Our problems, which often occur in online reverse auctions, generalize covering integer programs with multiplicity constraints (CIP), where we must fill up an R -dimensional bin by selecting (with a bounded number of repetitions) from a set of R -dimensional items, such that the overall cost is minimized. Thus, both DSP and DST are NP-hard, already for a single good, and hard to approximate for arbitrary number of goods. In this paper we focus on finding efficient approximations for DSP and DST instances where the number of goods is some fixed constant. In particular, we develop polynomial time approximation schemes (PTAS) for several subclasses of instances of practical interest. Our results include a PTAS for CIP in fixed dimension, and a more efficient (combinatorial) scheme for C I P ∞ , where the multiplicity constraints are omitted. Our approximation scheme for C I P ∞ is based on a non-trivial application of the fast scheme for the fractional covering problem, proposed by Fleischer [L. Fleischer, A fast approximation scheme for fractional covering problems with variable upper bounds, in: Proc. of the 15th ACM-SIAM Symposium on Discrete Algorithm, 2004, pp. 994–1003].

Analysis of the core of multisided Böhm-Bawerk assignment markets

We introduce the class of multisided Bohm-Bawerk assignment games which generalizes the well-known two-sided Bohm-Bawerk assignment games to markets with an arbitrary number of sectors. We reach the core and the corresponding extreme allocations of any multisided Bohm-Bawerk assignment game by means of an associated convex game defined on the set of sectors instead of the set of sellers and buyers. We also study when the core of a multisided Bohm-Bawerk assignment game is stable in the sense of von Neumann–Morgenstern.

PAIRWISE STABILITY IN A TWO-SIDED MATCHING MARKET WITH INDIVISIBLE GOODS AND MONEY

We consider a two-sided matching market in which the traders are partitioned into two sets; the set of sellers and the set of buyers. Each seller owns at most one indivisible good and each buyer owns a certain amount of money. Money is assumed to be an integer variable. Each trader can trade with at most one trader of the opposite side. The marriage model of Gale and Shapley is a special case of our model. We give a constructive proof to show the existence of a pairwise stable outcome.

Evolutionary stability of auction and supply chain contracting: An analysis based on disintermediation in the Indian tea supply chains

The purpose of this paper is to show that evolutionary stable market equilibrium is achievable through complete disintermediation of auctioneers if the option of bargaining-based supply chain contracting exists. The paper analyzes the evolutionary dynamics of a market that caters both the scopes of auction-intermediation and supply chain contracting to a set of homogeneous buyers and sellers. The motivation of this work developed from the contradiction between the theoretical framework of Lu and McAfee (1996) that identifies auction to be evolutionary stable over bargaining and the real instance of sustained disintermediation of auctioneers in the world’s largest tea industry in India where supply chain contracting is the other option of trading.

Qualitative One-to-Many Multi-Issue Negotiation: Approximating the QVA

When there is one buyer interested in obtaining a service from one of a set of sellers, multi-attribute or multi-issue auctions can ensure an allocation that is efficient. Even when there is no transferable utility (e.g., money), a recent qualitative version of the Vickrey auction may be used, the QVA, to obtain a Pareto-efficient outcome where the best seller wins. However, auctions generally require that the preferences of at least one party participating in the auction are publicly known, while often making this information public is costly, undesirable, or even impossible. It would therefore be useful to have a method that does not impose such a requirement, but is still able to approximate the outcome of such an auction. The main question addressed here is whether the Pareto-efficient best-seller outcome in multi-issue settings without transferable utility (such as determined by the QVA) can be reasonably approximated by multi-bilateral closed negotiation between a buyer and multiple sellers. In these closed negotiations parties do not reveal their preferences explicitly, but make alternating offers. The main idea is to have multiple rounds of such negotiations. We study three different variants of such a protocol: one that restricts the set of allowed offers for both the buyer and the seller, one where the winning offer is announced after every round, and one where the sellers are only told whether they have won or not after every round. It is shown experimentally that this protocol enables agents that can learn preferences to obtain agreements that approximate the Pareto-efficient best-seller outcome as defined by the auction mechanism. We also show that the strategy that exploits such a learning capability in negotiation is robust against and dominates a Zero Intelligence strategy. It thus follows that the requirement to publicly announce preferences can be removed when negotiating parties are equipped with the proper learning capabilities and negotiate using the proposed multi-round multi-bilateral negotiation protocol.

Adjusting prices in the multiple-partners assignment game

Starting with an initial price vector, prices are adjusted in order to eliminate the excess demand and at the same time to keep the transfers to the sellers as low as possible. In each step of the auction, to which set of sellers should those transfers be made is the key issue in the description of the algorithm. We assume additively separable utilities and introduce a novel distinction by considering multiple sellers owing multiple identical objects and multiple buyers with an exogenously defined quota, consuming more than one object but at most one unit of a seller’s good and having multi-dimensional payoffs. This distinction induces a necessarily more complicated construction of the over-demanded sets than the constructions of these sets for the other assignment games. For this approach, our mechanism yields the buyer-optimal competitive equilibrium payoff, which equals the buyer-optimal stable payoff. The symmetry of the model allows to getting the seller-optimal stable payoff and the seller-optimal competitive equilibrium payoff can then be also derived.

A selling mechanism

For the assignment game, we propose the following selling mechanism: sellers, simultaneously, fix their prices first; then buyers, sequentially, decide which object to buy, if any. The first phase of the game determines the potential prices, while the second phase determines the actual matching. We prove that the set of subgame perfect equilibria in pure strategies in the strong sense of the mechanism coincides with the set of sellers' optimal stable outcomes when buyers use maximal strategies.

DYNAMIC TRADING IN A DURABLE GOOD MARKET WITH ASYMMETRIC INFORMATION*

We analyze a dynamic version of the Akerlof–Wilson “lemons” market in a competitive durable good setting. There is a fixed set of sellers with private information about the quality of their wares. The price mechanism sorts sellers of different qualities into different time periods—prices and average quality of goods traded increase over time. Goods of all qualities are traded in finite time. Market failure arises because of the waiting involved—particularly for sellers of better quality. The equilibrium path may exhibit intermediate breaks in trading.

Scaling Laws for the Market Microstructure of the Interdealer Broker Markets

We discuss a series of simple models for microstructure of a double auction without intermediaries. We specialize to those markets, such as interdealer broker markets, which are dominated by professional traders, who trade mainly through limit orders, watch markets closely, and move their limit order prices frequently. We model these markets as a set of buyers and a set of sellers, whose numbers vary in time, and who diffuse in price space and interact through an annihilation interaction. We seek to compute the purely statistical effects of the presence of large numbers of traders, as scaling laws on various measures of liquidity, and to this end we allow our model very few parameters. We find that the bid-offer spread scales as 1 over the square root of the deal rate. In addition we investigate the scaling of other intuitive relationships, such as the relationship between the fluctuations of the best bid/offer and the density of buyers and sellers. We then study this model and its scaling laws under the influence of random disturbances to trader drift, volatility, and entrance rate. We also study possible extensions to the model, such as the addition of market order traders, and an interaction that models momentum-type trading. Finally, we discuss how simulations may be carried out to study scaling in all of these settings, and how the models may be tested in actual markets.

A Revised Land Surface Parameterization (SiB2) for Atmospheric GCMS. Part II: The Generation of Global Fields of Terrestrial Biophysical Parameters from Satellite Data

Abstract The global parameter fields used in the revised Simple Biosphere Model (SiB2) of Sellers et al. are reviewed. The most important innovation over the earlier SiB1 parameter set of Dorman and Sellers is the use of satellite data to specify the time-varying phonological properties of FPAR, leaf area index. and canopy greenness fraction. This was done by processing a monthly 1° by 1° normalized difference vegetation index (NDVI) dataset obtained farm Advanced Very High Resolution Radiometer red and near-infrared data. Corrections were applied to the source NDVI dataset to account for (i) obvious anomalies in the data time series, (ii) the effect of variations in solar zenith angle, (iii) data dropouts in cold regions where a temperature threshold procedure designed to screen for clouds also eliminated cold land surface points, and (iv) persistent cloud cover in the Tropics. An outline of the procedures for calculating the land surface parameters from the corrected NDVI dataset is given, and a brief d...