Université Paris Dauphine-PSL

On rigid regular graphs and a problem of Babai and Pultr

A graph is rigid if it only admits the identity endomorphism. We determine the minimum number of vertices of a rigid 𝑑 -regular graph for every 𝑑 . This extends results of Baron and Imrich (1969). Two rigid graphs are further mutually rigid if there is no homomorphism from one to...

Periodic regime of Frank-Read source for a dislocation phase field model

We study a two-dimensional phase field model describing the motion of dislocations for a Frank-Read source when an applied shear stress produces a driving rate $ \sigma $. The level sets of the phase describe the dislocation curves and allow their change of topology. The phase so...

Ask every way, decide once: making AI decisions invariant to how a question is worded

A decision read off a model's probabilities—a classifier's score, a language model used as a judge, a typed-decision model—depends on how the question is worded. Option order and naming have label-free fixes; logical form has none. We ask each proposition under logically equivale...

Classical and Modern JSON Schema: A Tutorial

The last few years have seen the ubiquitous diffusion of JSON as one of the most widely used formats for publishing and interchanging data, as it combines the flexibility of semistructured data models with well-known data structures such as objects and arrays. While various schem...

‘Don’t forget to post it on LinkedIn’: Identity regulation and the assetization of employees’ online selves

What happens to employees’ sense of who they are online when their organization tells them how to present themselves on LinkedIn? Companies increasingly intervene in employees’ professional social media presence through training programs and internal policies, encouraging them to...

Foreign aid and power play: Political cycles in world bank’s procurement allocation

This paper examines the existence of political cycles in the awarding of World Bank procurement contracts around elections. We analyze elections in the home country of firms winning these contracts, distinguishing between firms based in the aid recipient country (i.e., domestic f...

The two square root laws of market impact and the role of sophisticated market participants

The goal of this paper is to disentangle the roles of volume and of participation rate in the price response of the market to a sequence of transactions. To do so, we are inspired the methodology introduced in (Quant. Finance 15 (2015) 1123–1135; Math. Finance 30 (2020) 1309–1336...

Faster Hamiltonian Monte Carlo by learning leapfrog scale: an offline randomized solution

Abstract We introduce a Hamiltonian Monte Carlo (HMC) methodology based on an offline empirical calibration of randomized leapfrog parameters. The approach, referred to as eHMC, where e stands for empirical, leverages importance sampling to construct an empirical distribution on...

Atenolol or Bisoprolol after Myocardial Infarction without Recorded Heart Failure

BACKGROUND: Beta-blockers are a cornerstone of therapy following myocardial infarction. The effect of different β-blockers on the outcomes of patients without heart failure after myocardial infarction is not well-studied. METHODS: This observational cohort study used administrati...

A nested factor model for equity markets: reconciling multifractal stock returns and rough index volatilities

The Nested factor model was introduced by Chicheportiche et al. to represent non-linear correlations between stocks. Stock returns are explained by a standard factor model, but the (log)-volatilities of factors and residuals are themselves decomposed into factor modes, with a com...

Noise through an Additional Variable for Mean Field Games Master Equation on Finite State Space

Abstract. This paper provides a mathematical study of the well-posedness of a master equation with terms modeling common noise on finite state space. In this setting, the solution of the master equation depends on an additional variable modeling the value of a stochastic process...