Stability, Strategy-Proofness, and Cumulative Offer Mechanisms

2020 ◽  
Author(s):  
John William Hatfield ◽  
Scott Duke Kominers ◽  
Alexander Westkamp
Keyword(s):  
Choice Function ◽  
The Other ◽  
Choice Functions ◽  
Strategy Proof ◽  
Unit Demand ◽  
Unique Mechanism ◽  
Strategy Proofness

Abstract We characterize when a stable and strategy-proof mechanism is guaranteed to exist in the setting of many-to-one matching with contracts. We introduce three novel conditions—observable substitutability, observable size monotonicity, and non-manipulability via contractual terms—and show that when these conditions are satisfied, the cumulative offer mechanism is the unique mechanism that is stable and strategy-proof (for workers). Moreover, we show that our three conditions are, in a sense, necessary: If the choice function of some firm fails any of our three conditions, we can construct unit-demand choice functions for the other firms such that no stable and strategy-proof mechanism exists. Thus, our results provide a rationale for the ubiquity of cumulative offer mechanisms in practice.

scholarly journals Local‐global equivalence in voting models: A characterization and applications

2021 ◽  
Vol 16 (4) ◽  
pp. 1195-1220
Author(s):  
Ujjwal Kumar ◽  
Souvik Roy ◽  
Arunava Sen ◽  
Sonal Yadav ◽  
Huaxia Zeng
Keyword(s):  
Social Choice ◽  
Choice Function ◽  
Social Choice Function ◽  
Choice Functions ◽  
Local Strategy ◽  
Social Choice Functions ◽  
True Type ◽  
Strategy Proof ◽  
Voting Models ◽  
Strategy Proofness

The paper considers a voting model where each voter's type is her preference. The type graph for a voter is a graph whose vertices are the possible types of the voter. Two vertices are connected by an edge in the graph if the associated types are “neighbors.” A social choice function is locally strategy‐proof if no type of a voter can gain by misrepresentation to a type that is a neighbor of her true type. A social choice function is strategy‐proof if no type of a voter can gain by misrepresentation to an arbitrary type. Local‐global equivalence (LGE) is satisfied if local strategy‐proofness implies strategy‐proofness. The paper identifies a condition on the graph that characterizes LGE. Our notion of “localness” is perfectly general. We use this feature of our model to identify notions of localness according to which various models of multidimensional voting satisfy LGE. Finally, we show that LGE for deterministic social choice functions does not imply LGE for random social choice functions.

scholarly journals Necessary and sufficient conditions for pairwise majority decisions on path-connected domains

2021 ◽  
Author(s):  
Madhuparna Karmokar ◽  
Souvik Roy ◽  
Ton Storcken
Keyword(s):  
Connected Domain ◽  
Majority Rule ◽  
Choice Function ◽  
Sufficient Conditions ◽  
Choice Functions ◽  
Group Strategy ◽  
Median Rule ◽  
Strategy Proof ◽  
Necessary And Sufficient ◽  
Path Connected

AbstractIn this paper, we consider choice functions that are unanimous, anonymous, symmetric, and group strategy-proof and consider domains that are single-peaked on some tree. We prove the following three results in this setting. First, there exists a unanimous, anonymous, symmetric, and group strategy-proof choice function on a path-connected domain if and only if the domain is single-peaked on a tree and the number of agents is odd. Second, a choice function is unanimous, anonymous, symmetric, and group strategy-proof on a single-peaked domain on a tree if and only if it is the pairwise majority rule (also known as the tree-median rule) and the number of agents is odd. Third, there exists a unanimous, anonymous, symmetric, and strategy-proof choice function on a strongly path-connected domain if and only if the domain is single-peaked on a tree and the number of agents is odd. As a corollary of these results, we obtain that there exists no unanimous, anonymous, symmetric, and group strategy-proof choice function on a path-connected domain if the number of agents is even.

scholarly journals Strategy-Proof and Non-Wasteful Multi-Unit Auction via Social Network

2020 ◽  
Vol 34 (02) ◽  
pp. 2062-2069
Author(s):  
Takehiro Kawasaki ◽  
Nathanael Barrot ◽  
Seiji Takanashi ◽  
Taiki Todo ◽  
Makoto Yokoo
Keyword(s):  
Social Network ◽  
Truth Telling ◽  
Worst Case ◽  
The Social ◽  
Comprehensive Comparison ◽  
Strategy Proof ◽  
Unit Demand ◽  
Social Surplus ◽  
Unit Unit ◽  
Strategy Proofness

Auctions via social network, pioneered by Li et al. (2017), have been attracting considerable attention in the literature of mechanism design for auctions. However, no known mechanism has satisfied strategy-proofness, non-deficit, non-wastefulness, and individual rationality for the multi-unit unit-demand auction, except for some naïve ones. In this paper, we first propose a mechanism that satisfies all the above properties. We then make a comprehensive comparison with two naïve mechanisms, showing that the proposed mechanism dominates them in social surplus, seller's revenue, and incentive of buyers for truth-telling. We also analyze the characteristics of the social surplus and the revenue achieved by the proposed mechanism, including the constant approximability of the worst-case efficiency loss and the complexity of optimizing revenue from the seller's perspective.

A Comment on Arrow’s Impossibility Theorem

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Alec Sandroni ◽  
Alvaro Sandroni
Keyword(s):  
Social Choice ◽  
Choice Function ◽  
Social Preference ◽  
Social Choice Function ◽  
Individual Preference ◽  
Impossibility Theorem ◽  
Preference Order ◽  
Individual Choice ◽  
Choice Functions ◽  
Preference Orders

AbstractArrow (1950) famously showed the impossibility of aggregating individual preference orders into a social preference order (together with basic desiderata). This paper shows that it is possible to aggregate individual choice functions, that satisfy almost any condition weaker than WARP, into a social choice function that satisfy the same condition (and also Arrow’s desiderata).

Smooth approximations by continuous choice-functions

2021 ◽  
Author(s):  
Mihai Prunescu
Keyword(s):  
Error Bound ◽  
Common Sense ◽  
Choice Function ◽  
Continuous Functions ◽  
Ordered Sets ◽  
Choice Functions ◽  
Continuous Choice ◽  
Functions Of Two Variables ◽  
Smooth Approximations

Abstract We explore the existence of rational-valued approximation processes by continuous functions of two variables, such that the output continuously depends of the imposed error-bound. To this sake we prove that the theory of densely ordered sets with generic predicates is ℵ0- categorical. A model of the theory and a particular continuous choice-function are constructed. This function transfers to all other models by the respective isomorphisms. If some common-sense conditions are fulfilled, the processes are computable. As a byproduct, other functions with surprising properties can be constructed.

scholarly journals Sequentially Rationalizable Choice

2007 ◽  
Vol 97 (5) ◽  
pp. 1824-1839 ◽  
Author(s):  
Paola Manzini ◽  
Marco Mariotti
Keyword(s):  
Choice Function ◽  
Binary Relations ◽  
Choice Functions ◽  
Choice Problem ◽  
Full Characterization ◽  
Human Choice ◽  
Fixed Set ◽  
Rationalizable Choice

A sequentially rationalizable choice function is a choice function that can be retrieved by applying sequentially to each choice problem the same fixed set of asymmetric binary relations (rationales) to remove inferior alternatives. These concepts translate into economic language some human choice heuristics studied in psychology and explain cyclical patterns of choice observed in experiments. We study some properties of sequential rationalizability and provide a full characterization of choice functions rationalizable by two and three rationales. (JEL D01).

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