walrasian equilibrium with gross substitutes in this paper we study the problem of efficient production and allocation of indivisible objects among a set of consumers we assume that the agents preferences depend on the bundle of objects and the quantity of money they consume furthermore we assume that preferences are quasilinear in money and that agents have a large endowment of money with indivisibilities it is well known that many familiar properties of the utility functions fail to ensure existence in their striking analysis of the matching problem kelso and crawford 5 introduce the gross substitutes gs condition which ensures the non emptiness of the core we propose two new conditions and show that with quasilinearity they are equivalent article id jeth 1999 2531 available online at http www idealibrary com on

matching with contracts comment abstract the matching with contracts model hatfield and milgrom 2005 is widely considered to be one of the most important advances of the last two decades in matching theory one of their main messages is that the set of stable allocations is non empty under a substitutes condition we show that an additional irrelevance of rejected contracts irc condition is implicitly assumed throughout their analysis and in the absence of irc several of their results including the guaranteed existence of a stable allocation fail to hold jel c78 d86

enhanced lateral transshipments in a multi location inventory system in managing an inventory network two approaches to the pooling of stock have been proposed reactive transshipments respond to shortages at a location by moving inventory from elsewhere within the network while proactive stock redistribution seeks to minimize the chance of future stockouts this paper is the first to propose an enhanced reactive approach in which individual transshipments are viewed as an opportunity for proactive stock redistribution we adopt a quasi myopic approach to the development of a strongly performing enhanced reactive transshipment policy in comparison to a purely reactive approach to transshipment service levels are improved while a reduction in safety stock levels is achieved the aggregate costs incurred in managing the system are significantly reduced especially so for large networks moreover an optimal policy is determined for small networks and it is shown that the enhanced reactive policy substantially closes the gap to optimality

a semi markov decision problem for proactive and reactive transshipments between multiple warehouses abstract lateral transshipments are an effective strategy to pool inventories we present a semi markov decision problem formulation for proactive and reactive transshipments in a multi location continuous review distribution inventory system with poisson demand and one for one replenishment policy for a two location model we state the monotonicity of an optimal policy in a numerical study we compare the benefits of proactive and different reactive transshipment rules the benefits of proactive transshipments are the largest for networks with intermediate opportunities of demand pooling and the difference between alternative reactive transshipment rules is negligible

comparative statics in matching markets abstract this paper studies the comparative statics of adding agents to matching markets that generalize the marriage and college admissions markets of d gale and l shapley amer math monthly 69 1962 9 15 it is shown for the wide class of matching markets studied by a roth econometrica 52 1984 47 57 that adding an agent to one side of the market weakens the competitive positions of the other agents on that side and strengthens the competitive positions of the agents on the other side

on stable and strategy proof rules in matching markets with contracts abstract this paper studies stable and one sided strategy proof rules in many to one matching markets with contracts not assuming any kind of substitutes condition or the law of aggregate demand we obtain the following results first the number of stable and strategy proof rules is at most one second the doctor optimal stable rule whenever it exists is the unique candidate for a stable and strategy proof rule third a stable and strategy proof rule whenever it exists is second best optimal for doctor welfare in that no individually rational and strategy proof rule can dominate it this last result is further generalized to non wasteful and strategy proof rules due to the weak assumptions our analysis covers a broad range of markets including cases where a unique stable and strategy proof rule is not equal to the one induced by the cumulative offer process or the deferred acceptance algorithm

substitutes and stability for matching with contracts we consider the matching problem with contracts of hatfield and milgrom 2005 and we introduce new concepts of bilateral and unilateral substitutes we show that bilateral substitutes is a sucient condition for the existence of a stable allocation in this framework however the set of stable allocations does not form a lattice under this condition and there does not necessarily exist a doctor optimal stable allocation under a slightly stronger condition unilateral substitutes the set of stable allocations still does not necessarily form a lattice with respect to doctors preferences but there does exist a doctor optimal stable allocation and other key results such as incentive compatibility and the rural hospitals theorem are recovered

protection or expropriation politically connected independent directors in china abstract this paper empirically investigates politically connected independent directors among chinese listed firms using 7487 firm year observations from the shanghai stock exchange during the period of 2003 2012 we distinguish between privately controlled firms and state controlled firms we find that the value effect and incentives of appointing independent directors with political ties are shaped by a firm s ownership structure more exactly chinese listed privately controlled firms with a large fraction of politically connected independent directors tend to outperform their non connected counterparts due to the ease of access to external debt financing and more subsidies from the government however the appointment of politically connected independent directors also enlarges the magnitude of related party transactions with the controlling party in listed privately controlled firms in contrast having politicians as independent directors does not help to add value to listed state controlled firms especially firms controlled by the local government due to the expropriation of minority investors via more related party transactions and more severe over investment problems

on the correspondence of contracts to salaries in many to many matching abstract in this note i extend the work of echenique 2012 to show that a model of many to many matching with contracts may be embedded into a model of many to many matching with wage bargaining whenever 1 all agents preferences are substitutable and 2 the matching with contracts model is unitary in the sense that every contractual relationship between a given firm worker pair is specified in a single contract conversely i show that unitarity is essentially necessary for the embedding result

approximate dynamic programming for lateral transshipment problems in multi location inventory systems abstract companies commonly allocate their inventories across multiple locations based on their historical sales rates however random fluctuations in customer purchases such as those caused by weather conditions and other external factors might cause significant deviations from expected demand leading to excess stock in some locations and stockouts in others to fix this mismatch companies often turn to lateral transshipments e g the movement of stock between locations of the same echelon in this paper we examine multi location inventory systems under periodic review with multiple opportunities for proactive transshipments within one order cycle if stockouts occur demand is lost with no opportunity to backorder the objective of our model is to find an optimal policy that indicates the sources and the destinations of transshipments as well as the number of units to maximise the profit of the network we create a dynamic program that can in principal be solved to optimality using bellman s equation however the size of the state and decision spaces makes it impossible to find the optimal policy for real world sized problem instances thereby we use forward approximate dynamic programming to find a near optimal transshipment policy finally we conduct an extensive numerical study to gauge the performance of our transshipment policy for small size instances we compare our policy to the optimal one for larger scale instances we consider other practically oriented heuristics our numerical experiments show that our proposed algorithm performs very well compared to state of the art methods in the literature

dynamic balancing of inventory in supply chains abstract we consider the dynamic version of the classic problem of allocation of inventories to a set of retailers to rectify the imbalance of inventories amongst them while most research is focussed on analyzing different allocation strategies with a predetermined time of shipment static policy we investigate the benefit of using real time demand inventory information to schedule rebalancing shipments in a retail network we model the dynamic rebalancing problem that has two decisions the timing of the balancing shipments and determination of the new stocking levels at the retailers as a dynamic program dp we obtain structural properties for the optimal allocation rebalancing and timing strategies we also present conditions under which a greedy heuristic to decide how much to ship from one retailer to another is optimal the dp for determining the optimal timing and quantity of shipments has a very large state space we present an algorithm to solve this dp efficiently we also provide a heuristic solution procedure to the dynamic problem that performs very close to optimal numerical results show that dynamic allocation policies can lead to substantial benefits over the static policy especially in systems in which the starting inventories at the retailers are balanced or when high service levels are required

sequential rules for house allocation with price restrictions this paper considers a housing market with price restrictions on such markets the existence of a unique minimum rationing equilibrium price vector has been established for each preference profile on a general preference domain that contains almost all preference profiles this vector can be used as a key ingredient in a direct and strategy proof allocation mechanism the main contribution of this paper is to provide two price sequences one with increasing prices and one with decreasing prices that both terminate to a minimal rationing equilibrium price vector in a finite number of steps these sequences are demonstrated to play key roles in an english auction and a dutch auction respectively for the considered housing market with price restrictions less

state enterprise relation local economic priority and corporate environmental responsibility this paper empirically investigates how the state enterprise relation and local government s economic priority affect corporate environmental responsibility in a sample of chinese polluting enterpr

contracts versus salaries in matching workers and firms may bargain over general multidimensional contracts they may negotiate over health benefits housing retirement plans etc substitutes on the other hand is the assumption commonly placed on firms preferences to guarantee the existence of stable matchings of workers and firms in this paper i show that when firms regard contracts as substitutes bargaining over contracts can be embedded into a model of bargaining over wages the economics of the embedding is straightforward except for a small twist when a firm and a worker negotiate over a contract they may bargain over many dimensions however the pareto frontier of contracts is in a sense one dimensional what is better for the worker is worse for the firm so pareto optimal contracts may be viewed as salaries with the better contracts for the firm meaning lower salaries and the better contracts for the worker meaning higher salaries the twist is that a firm s ranking over contracts might be affected by the firm s other hires for example health plan a may be better than b for a firm if it has many employees but b beats a if it has few when contracts are substitutes it turns out that the ranking is not affected in this way hatfield and milgrom 2005 present a model of two sided worker firm matching with contracts a firm will hire a collection of workers and will negotiate a contract with each one of them the model is a generalization of kelso and crawford 1982 where each firm and each worker negotiate a wage 1 kelso and crawford show that when firms demands satisfy gross substitutes the core of the matching market is nonempty hatfield and milgrom show that when the firms preferences over contracts satisfy their notion of substitutes the core of the market is nonempty i show that hatfield and milgrom s model can be embedded into the model of kelso and crawford hatfield and milgrom s assumption of substitutability enables an embedding where firms demands for workers satisfy kelso and crawford s notion of gross substitutes as a result the nonemptiness of the core follows from the argument in kelso and crawford and their salary adjustment algorithm finds a stable matching of workers to firms and a vector of supporting salaries hatfield and milgrom s paper is an elegant analysis of two sided matching it simplifies matching models and makes their relationship to auction models more transpar ent their paper contributes much more than showing the nonemptiness of the core when firms and workers can sign general contracts and my result does not diminish

do lenders favor politically connected firms rent provision in an emerging financial market corruption by the politically connected is often blamed for economic ills particularly in less developed economies using a loan level data set of more than 90 000 rms that represents the universe of corporate lending in pakistan between 1996 and 2002 we investigate rents to politically connected rms in banking classifying a rm as political if its director participates in an election we examine the extent nature and economic costs of political rent provision we nd that political rms borrow 45 percent more and have 50 percent higher default rates such preferential treatment occurs exclusively in government banks private banks provide no

competitive equilibria in two sided matching markets with general utility functions we present an exact characterization of utilities in competitive equilibria of two sided matching markets in which the utility of each agent depends on the choice of partner and the terms of the partnership potentially including monetary transfer examples of such markets include sellers and buyers or jobs and workers demange and gale showed that the set of competitive equilibria in this type of market forms a complete lattice with each extreme point of the lattice representing an equilibrium with the highest utilities for the agents on one side and the lowest utilities for the agents on the opposite side our characterization is based on establishing a connection between the competitive equilibria of a market and the competitive equilibria of certain strict subsets of that market each obtained by removing exactly one agent this characterization captures the effect of competition when agents are added to the market or removed from the market it gives a precise procedure for constructing competitive eq

unilateral substitutability implies substitutable completability in many to one matching with contracts abstract we prove that the unilateral substitutability property introduced in hatfield and kojima 2010 implies the substitutable completability property from hatfield and kominers 2014 this paper provides a novel linkage between these two sufficient conditions for the existence of a stable matching in many to one matching markets with contracts a substitutable completion of a preference is a substitutable preference created by adding some sets of contracts to the original preference order we provide an algorithm which when operated on the unilaterally substitutable preferences produces such a substitutable completion thus it provides a constructive proof of the connection between the two properties

some further properties of the cumulative offer process we investigate extension resource monotonicity and respecting improvements properties of the cumulative offer process cop extension monotonicity says that no doctor is to be better off whenever others start preferring more contracts to being unmatched resource monotonicity on the other hand requires that no doctor becomes worse off whenever hospitals start hiring more doctors the cop becomes extension and resource monotonic whenever contracts are unilateral substitutes us satisfying an irrelevance of rejected contracts condition irc this result implies that the cop is population monotonic under us and the irc we then turn to the respecting improvements property which states that no doctor should be harmed if some of his contracts become more popular with an additional law of aggregate demand condition we show that the cop respects improvements

matching with contracts we develop a model of matching with contracts which incorporates as special cases the college admissions problem the kelso crawford labor market matching model and ascending package auctions we introduce a new law of aggregate demand for the case of discrete heterogeneous workers and show that when workers are substitutes this law is satisfied by profit maximizing firms when workers are substitutes and the law is satisfied truthful reporting is a dominant strategy for workers in a worker offering auction matching algorithm we also parameterize a large class of preferences satisfying the two conditions

matching with branch of choice contracts at the united states military academy branch selection is a key decision in a cadet s military career cadets at usma can increase their branch priorities at a fraction of slots by extending their service agreement this real life matching problem lls an important gap in market design literature although priorities fail a key substitutes condition the agent optimal stable mechanism is well dened and in contrast to the current usma mechanism it is fair stable and strategy proof adoption of this mechanism benets cadets and the army this new

understanding preferences demand types and the existence of equilibrium with indivisibilities we propose new techniques for understanding agents valuations our classification into demand types incorporates existing definitions substitutes complements strong substitutes etc and permits new ones our unimodularity theorem generalises previous results about when competitive equilibrium exists for any set of agents whose valuations are all of a demand type for indivisible goods contrary to popular belief equilibrium is guaranteed for more classes of purely complements than of purely substitutes preferences our intersection count theorem checks equilibrium existence for combinations of agents with specific valuations by counting the intersection points of geometric objects applications include matching and coalition formation and the product mix auction introduced by the bank of england in response to the financial crisis

political connections and the process of going public evidence from china abstract we examine how political connections impact the process of going public specifically we test how political connections impact the pricing of the newly offered shares the magnitude of underpricing and the fixed cost of going public based on the experience of the newly public firms from chinese security markets and using multiple measures of political connections we find robust evidence that the issuing firms with political connections reap significant preferential benefits in the process of going public to be specific we find that firms irrespective of their ownership status with greater political connections have relatively higher offering price lower underpricing and lower fixed costs during the going public process

optimal and approximate policies in multiperiod multilocation inventory models with transshipments this paper examines the effects on the optimal ordering policy and its cost of allowing for interactions among retail outlets specifically transshipments are allowed as recourse actions occurring after demands are realized but before they must be satisfied the resultant savings in holding and shortage costs are balanced against the costs of transshipment a base stock ordering policy is optimal for this model if the final period base stock order up to point is nonnegative then it will be the base stock order up to point for all periods unfortunately it can be found analytically only for two special cases where either the cost parameters are equal at every outlet or there are only two outlets these two special cases are used to validate a heuristic solution technique employing monte carlo integration which is then compared to an easily calculated base policy in order to gauge the contribution of this model the additional savings from using this heuristic policy are significant particularly for problems with many retail outlets and low transshipment costs

how to control controlled school choice we characterize choice rules for schools that regard students as substitutes while expressing preferences for a diverse student body the stable or fair assignment of students to schools requires the latter to regard the former as substitutes such a requirement is in conflict with the reality of schools preferences for diversity we show that the conflict can be useful in the sense that certain unique rules emerge from imposing both considerations we also provide welfare comparisons for students when different choice rules are employed

relaxing the substitutes condition in matching markets with contracts in the many to one matching model with contracts i provide new necessary and new sufficient conditions for the existence of a stable allocation these new conditions exploit the fact that one side of the market has strict preferences over individual contracts

an inventory model with unidirectional lateral transshipments this paper deals with a continuous review inventory system with poisson demand in which lateral transshipments are allowed in case of a shortage at a location another location acts as a supplier if it is possible a common assumption in earlier papers is that transshipments are allowed between all locations this network configuration may however not be the best choice for many reasons one such reason is that it may be difficult to establish contracts between locations regarding the design of the transshipment policy another reason is that a system with many transshipment links is much more complex than a system with few transshipment links in this paper we study a system where transshipments are allowed only in one direction this may be a reasonable policy if the locations have very different backorder lost sales costs our approach is relatively simple and fast and works well in most cases

cumulative offer process is order independent this note shows that in the matching with contracts model the outcome of the cumulative offer process is order independent if every hospital has a choice function that satisfies the bilateral substitutability condition and the irrelevance of rejected contracts condition

bidding for army career specialties improving the rotc branching mechanism motivated by the low retention rates of us military academy and reserve officer training corps graduates the army recently introduced incentives programs in which cadets could bid 3 years of additional service obligation to obtain higher priority for their desired branches the full potential of this incentives program is not utilized because of the rotc s deficient matching mechanism i propose a design that eliminates these shortcomings and mitigates several policy problems the army has identified in contrast to the rotc mechanism my design utilizes market principles more extensively and it is a hybrid between a market mechanism and a priority based allocation mechanism