Martin Hoefer
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View article: Persuading Agents in Opinion Formation Games
Persuading Agents in Opinion Formation Games Open
Prominent opinion formation models such as the one by Friedkin and Johnsen (FJ) concentrate on the effects of peer pressure on public opinions. In practice, opinion formation is also based on information about the state of the world and pe…
View article: Welfare and Beyond in Multi-Agent Contracts
Welfare and Beyond in Multi-Agent Contracts Open
A principal delegates a project to a team $S$ from a pool of $n$ agents. The project's value if all agents in $S$ exert costly effort is $f(S)$. To incentivize the agents to participate, the principal assigns each agent $i\in S$ a share $ρ…
View article: Fractional Claims Trades and Donations in Financial Networks
Fractional Claims Trades and Donations in Financial Networks Open
Exploring measures to improve financial networks and mitigate systemic risks is an ongoing challenge. We study claims trading, a notion defined in Chapter 11 of the U.S. Bankruptcy Code. For a bank $v$ in distress and a trading partner $w$…
View article: Dynamic Debt Swapping in Financial Networks
Dynamic Debt Swapping in Financial Networks Open
A debt swap is an elementary edge swap in a directed, weighted graph, where two edges with the same weight swap their targets. Debt swaps are a natural and appealing operation in financial networks, in which nodes are banks and edges repre…
View article: Algorithmic Persuasion with Evidence
Algorithmic Persuasion with Evidence Open
In a game of persuasion with evidence, a sender has private information. By presenting evidence on the information, the sender wishes to persuade a receiver to take a single action (e.g., hire a job candidate, or convict a defendant). The …
View article: Delegated online search
Delegated online search Open
In a delegation problem, a principal P with commitment power tries to pick one out of n options. Each option is drawn independently from a known distribution. Instead of inspecting the options herself, P delegates the information acquisiti…
View article: Best of Both Worlds: Agents with Entitlements
Best of Both Worlds: Agents with Entitlements Open
Fair division of indivisible goods is a central challenge in artificial intelligence. For many prominent fairness criteria including envy-freeness (EF) or proportionality (PROP), no allocations satisfying these criteria might exist. Two po…
View article: Designing Exploration Contracts
Designing Exploration Contracts Open
We study a natural application of contract design in the context of sequential exploration problems. In our principal-agent setting, a search task is delegated to an agent. The agent performs a sequential exploration of $n$ boxes, suffers …
View article: Algorithms for Claims Trading
Algorithms for Claims Trading Open
The recent banking crisis has again emphasized the importance of understanding and mitigating systemic risk in financial networks. In this paper, we study a market-driven approach to rescue a bank in distress based on the idea of claims tr…
View article: Competitive Equilibria with a Constant Number of Chores
Competitive Equilibria with a Constant Number of Chores Open
We study markets with mixed manna, where m divisible goods and chores shall be divided among n agents to obtain a competitive equilibrium. Equilibrium allocations are known to satisfy many fairness and efficiency conditions. While a lot of…
View article: Information Design for Congestion Games with Unknown Demand
Information Design for Congestion Games with Unknown Demand Open
We study a novel approach to information design in the standard traffic model of network congestion games. It captures the natural condition that the demand is unknown to the users of the network. A principal (e.g., a mobility service) com…
View article: Threshold testing and semi-online prophet inequalities
Threshold testing and semi-online prophet inequalities Open
We study threshold testing, an elementary probing model with the goal to choose a large value out of n i.i.d. random variables. An algorithm can test each variable X_i once for some threshold t_i, and the test returns binary feedback wheth…
View article: Delegated Online Search
Delegated Online Search Open
In a delegation problem, a principal P with commitment power tries to pick one out of n options. Each option is drawn independently from a known distribution. Instead of inspecting the options herself, P delegates the information acquisiti…
View article: Fully Polynomial-Time Algorithms Parameterized by Vertex Integrity Using Fast Matrix Multiplication
Fully Polynomial-Time Algorithms Parameterized by Vertex Integrity Using Fast Matrix Multiplication Open
We study the computational complexity of several polynomial-time-solvable graph problems parameterized by vertex integrity, a measure of a graph’s vulnerability to vertex removal in terms of connectivity. Vertex integrity is the smallest n…
View article: Best of Both Worlds: Agents with Entitlements
Best of Both Worlds: Agents with Entitlements Open
Fair division of indivisible goods is a central challenge in artificial intelligence. For many prominent fairness criteria including envy-freeness (EF) or proportionality (PROP), no allocations satisfying these criteria might exist. Two po…
View article: Maximizing Nash Social Welfare in 2-Value Instances: Delineating Tractability
Maximizing Nash Social Welfare in 2-Value Instances: Delineating Tractability Open
We study the problem of allocating a set of indivisible goods among a set of agents with \emph{2-value additive valuations}. In this setting, each good is valued either $1$ or $\sfrac{p}{q}$, for some fixed co-prime numbers $p,q\in \NN$ su…
View article: Equilibria and Convergence in Fire Sale Games
Equilibria and Convergence in Fire Sale Games Open
The complex interactions between algorithmic trading agents can have a severe influence on the functioning of our economy, as witnessed by recent banking crises and trading anomalies. A common phenomenon in these situations are fire sales,…
View article: Maximizing Nash Social Welfare in 2-Value Instances
Maximizing Nash Social Welfare in 2-Value Instances Open
We consider the problem of maximizing the Nash social welfare when allocating a set G of indivisible goods to a set N of agents. We study instances, in which all agents have 2-value additive valuations: The value of every agent for every g…
View article: Seniorities and Minimal Clearing in Financial Network Games
Seniorities and Minimal Clearing in Financial Network Games Open
Financial network games model payment incentives in the context of networked liabilities. In this paper, we advance the understanding of incentives in financial networks in two important directions: minimal clearing (arising, e.g., as a re…
View article: Public Signals in Network Congestion Games
Public Signals in Network Congestion Games Open
We consider a largely untapped potential for the improvement of traffic networks that is rooted in the inherent uncertainty of travel times. Travel times are subject to stochastic uncertainty resulting from various parameters such as weath…
View article: Fair Division of Indivisible Goods for a Class of Concave Valuations
Fair Division of Indivisible Goods for a Class of Concave Valuations Open
We study the fair and efficient allocation of a set of indivisible goods among agents, where each good has several copies, and each agent has an additively separable concave valuation function with a threshold. These valuations capture the…
View article: Delegated Online Search
Delegated Online Search Open
In a delegation problem, a principal P with commitment power tries to pick one out of $n$ options. Each option is drawn independently from a known distribution. Instead of inspecting the options herself, P delegates the information acquisi…
View article: Algorithms for Persuasion with Limited Communication
Algorithms for Persuasion with Limited Communication Open
The Bayesian persuasion paradigm of strategic communication models interaction between a privately informed sender and an ignorant but rational receiver. The goal is typically to design a (near-)optimal communication (or signaling) scheme …
View article: Asynchronous Opinion Dynamics in Social Networks
Asynchronous Opinion Dynamics in Social Networks Open
Opinion spreading in a society decides the fate of elections, the success of products, and the impact of political or social movements. The model by Hegselmann and Krause is a well-known theoretical model to study such opinion formation pr…
View article: Stochastic Probing with Increasing Precision
Stochastic Probing with Increasing Precision Open
We consider a selection problem with stochastic probing. There is a set of items whose values are drawn from independent distributions. The distributions are known in advance. Each item can be \emph{tested} repeatedly. Each test reduces th…
View article: Approximating Nash Social Welfare in 2-Valued Instances.
Approximating Nash Social Welfare in 2-Valued Instances. Open
We consider the problem of maximizing the Nash social welfare when allocating a set $\mathcal{G}$ of goods to a set $\mathcal{N}$ of agents. We study instances, in which all agents have 2-valued additive valuations. In such an instance, th…
View article: Maximizing Nash Social Welfare in 2-Value Instances
Maximizing Nash Social Welfare in 2-Value Instances Open
We consider the problem of maximizing the Nash social welfare when allocating a set $\mathcal{G}$ of indivisible goods to a set $\mathcal{N}$ of agents. We study instances, in which all agents have 2-value additive valuations: The value of…