Develops a novel inverse optimization method for choosing convex risk functions.
problem Challenges in choosing convex risk functions that accurately represent risk preferences.
method Inverse optimization framework incorporating properties of convex risk functions and individual feedbacks.
result Generates risk functions that make forward optimization problems optimal.
Optimal risk sharing without convex preferences using aggregate convexity.
problem Risk sharing among non-convex preferences.
method Aggregate convexity principles and Lyapunov convexity, combined with approximation arguments for law invariant risk measures.
result Derivation of a computationally tractable formula for the conjugate of the value function.
Introduces GG-convex risk measures and derives their dual representations.
problem Defining and studying GG-convex risk measures.
method Introduces GG-convex conjugate, derives dual representations, and studies Orlicz risk measures.
result Derives a general dual representation for GG-convex risk measures.
Constructs new elicitable risk measures with multiplicative scoring functions.
problem Defining new elicitable risk measures with specific properties.
method Constructs new elicitable risk measures using a multiplicative scoring function.
result Encompasses and allows construction of novel elicitable risk measures.
Least Squares Estimators are suboptimal for 5D convex functions.
problem Suboptimality of Least Squares Estimators in estimating multidimensional convex functions.
method Analysis of natural subclasses of convex functions in random and fixed design settings.
result Risk of LSE is n−2/d while minimax risk is n−4/(d+4) for d≥5. Paper studies convex risk measures linked to optimization.
problem Risk assessment in finance and insurance.
method Investigates a wide class of risk measures on Orlicz spaces.
result Characterizes the dual of risk measures and provides complementary representations.
New insights into risk aversion for complex decision models.
problem Understanding risk aversion in non-monotone decision models.
method Characterization of probabilistic risk aversion for generalized rank-dependent functions.
result Probabilistic risk aversion is determined by the distortion function, which is convex or scaled quantile-spread mixtures.
Submodularity is studied for convex risk measures, including Expected Shortfall.
problem Characterizing submodularity in convex risk measures.
method Analyzing submodularity properties of law-invariant coherent risk measures, including Expected Shortfall and Value-at-Risk.
result AES is submodular only when it reduces to ES, and empirical analysis shows AES violations are less frequent than VaR and ES violations.
The paper analyzes elicitability of return risk measures and their scoring functions.
problem Elicitability of return risk measures and their scoring functions.
method Dual representation results for convex and geometrically convex return risk measures, axiomatic characterizations of Orlicz premia, and construction of strictly consistent scoring functions.
result Orlicz premia are the only elicitable return risk measures under different sets of conditions.
This paper gives an overview of the theory of dynamic convex risk measures for random variables in discrete time setting. We summarize robust representation results of conditional convex risk measures, and we characterize various time consistency properties of dynamic risk measures in terms of acceptance sets, penalty …
A new RL framework for risk-sensitive decision-making using convex scoring functions.
problem Time-inconsistent risk measures in reinforcement learning.
method Convex scoring functions, augmented state space, auxiliary variable, customized Actor-Critic algorithm.
result Theoretical guarantees for approximation and convergence under certain conditions.
Paper characterizes monotonic mean-deviation risk measures.
problem Developing consistent risk measures from mean-deviation models.
method Applying a risk-weighting function to the deviation part of a mean-deviation model.
result Characterizes monotonic mean-deviation measures as consistent risk measures.
Paper improves privacy in ERM with faster algorithms and broader applicability.
problem Privacy-preserving machine learning with empirical risk minimization.
method Develops faster algorithms for differentially private ERM in various settings.
result Achieves optimal or near-optimal utility bounds with less gradient complexity.
Establishes relationships between prudence and stability properties of risk functionals.
problem Stability properties of risk functionals
method General relationships and preservation of prudence under cash-additive hulls and inf-convolutions
result General methods for constructing prudent risk measures
Study dynamic risk measures with distributional uncertainty using optimal transport.
problem Risk robustification under distributional uncertainty in Markovian models.
method Characterize risk measures via convex monotone semigroups and optimal transport costs.
result Identify generator and correction terms for dynamic risk measures under different scaling regimes.
This paper improves stochastic approximation for smooth and strongly convex functions.
problem Improving convergence rate of stochastic approximation for smooth and strongly convex functions.
method Utilizes both smoothness and strong convexity conditions to achieve faster convergence rates.
result Demonstrates an O(1/[λTα]+κF∗/T) risk bound, potentially faster than O(1/[λT]). New algorithms help machines forget old data efficiently.
problem Machine learning models can retain old data, hindering new learning.
method Developed TV-stable algorithms based on noisy SGD for convex and non-convex functions.
result Achieved efficient unlearning with upper and lower bounds on risk.
Study landscape of non-convex empirical risk with degenerate population risk.
problem Degenerate non-convex population risk in machine learning problems.
method Analyze population risk first, then connect to empirical risk landscape.
result Established correspondence between empirical and population risk critical points.
Estimates risk in finance using Wasserstein distance and parametric models.
problem Assessing risk in financial models with model uncertainty.
method Parametric approach based on Wasserstein distance for convex risk functionals.
result Developed a numerical method using neural networks to estimate risk and optimal perturbations.
This paper tackles minimizing clipped convex functions with heuristics and mixed-integer convex programming.
problem Minimizing a sum of clipped convex functions.
method Heuristics and mixed-integer convex programming.
result Heuristics can find good solutions, and the perspective transformation yields tractable lower bounds.
The paper characterizes dynamic return and star-shaped risk measures via BSDEs.
problem Characterizing dynamic return and star-shaped risk measures.
method Characterization of star-shaped functionals and BSDEs.
result Existence of convex BSDEs with non-empty set of supersolutions.
The paper bounds payoffs and option prices in discrete models.
problem Measuring risk in discrete models and incomplete markets.
method Analytical and simulated bounds for payoff functions and option prices.
result Analytical and simulated bounds for European and American options.
Study risk bounds for distributed ERM with general loss functions and hypothesis spaces.
problem Limited theoretical analysis for distributed ERM with general loss functions and hypothesis spaces.
method Derive tight risk bounds under assumptions on hypothesis space and loss function.
result Developed more general risk bound for distributed ERM without strong convexity restriction.
New method uses DC functions for piecewise linear regression.
problem Regression with piecewise linear constraints.
method Estimates piecewise linear convex functions using a difference of convex functions.
result Method achieves close to minimax statistical risk and comparable performance to existing methods.
Paper improves privacy-preserving optimization rates for convex functions.
problem Differentially private stochastic convex optimization.
method Algorithmic improvements for convex and strongly convex functions under TNC and non-negative loss.
result Excess population risk bounds for DP-SCO are faster than previous results.
New findings on how certain functionals behave in random variable spaces.
problem Understanding when law-invariant convex functionals simplify to the mean.
method Analyzing a broad class of random variable spaces and mild semicontinuity assumptions.
result The expectation functional is the only law-invariant convex functional that collapses to the mean under certain conditions.
This paper optimizes performative risk by focusing on convex properties and developing efficient algorithms.
problem Performative risk, the loss experienced by decision makers, is not optimized by stable models.
method Identifying convex properties of loss function and model-induced distribution shift, developing algorithms for optimization.
result Optimization of performative risk with better sample efficiency than generic methods.
Equivalent characterizations of multiportfolio time consistency are deduced for closed convex and coherent set-valued risk measures on Lp(Ω,F,P;Rd) with image space in the power set of Lp(Ω,Ft,P;Rd). In the convex case, multiportfolio time consistency is equivalent to a cocycle condition on…
The paper tackles performative risk optimization under weak convexity assumptions.
problem Optimizing performative risk in a closed-loop prediction system with weak convexity.
method Relaxing convexity assumptions to maintain optimization feasibility.
result Iterative optimization methods remain applicable even with weakened convexity conditions.
Novel convex surrogate for non-modular loss functions.
problem Computational tractability for non-modular loss functions.
method Submodular-supermodular decomposition, slack-rescaling, Lov{á}sz hinge.
result First tractable solution for non-modular loss functions.
Boosted Difference of Convex Functions Algorithm solves VaR constrained portfolio optimization.
problem Designing VaR optimal portfolios under financial regulations.
method Boosted Difference of Convex Functions Algorithm (BDCA) with a novel line search framework.
result BDCA linearly converges to a Karush-Kuhn-Tucker point for VaR constrained portfolio problems.
New framework for managing medical risks using convex responses.
problem Medical risk management and dosing optimization.
method Analyzes convex and concave dose-response functions, defines antifragility.
result Proposes a mathematical framework for integrating nonlinearities in oncology.
The purpose of this paper is to give a selective survey on recent progress in random metric theory and its applications to conditional risk measures. This paper includes eight sections. Section 1 is a longer introduction, which gives a brief introduction to random metric theory, risk measures and conditional risk measu…
The paper characterizes law-invariant star-shaped risk measures.
problem Understanding and characterizing law-invariant star-shaped risk measures.
method Developed characterizations for positively homogeneous and star-shaped functionals, derived Kusuoka-type representations, and offered representations of general law-invariant star-shaped functionals.
result Characterizations of law-invariant star-shaped functionals, including their connections to Value-at-Risk and Expected Shortfall.
The paper derives robust dualities for pricing and hedging in financial markets.
problem Tackles pricing and hedging of contingent claims in financial markets with various constraints.
method Derives dualities for super- and subhedging, considering strict and relaxed versions.
result Yields tighter price bounds and robust hedging strategies.
Investigates conditions for risk or utility functionals to be sensitive to large losses.
problem Conditions for risk or utility functionals to be sensitive to large losses.
method Analyzes sensitivity to large losses for various risk and utility functionals.
result Value at Risk and Expected Shortfall generally fail to be sensitive to large losses, but expected utility functionals and certain adjusted versions are sensitive.
In an incomplete Brownian-motion market setting, we propose a convex monotonic pricing functional for nonattainable bounded contingent claims which is compatible with prices for attainable claims. The pricing functional is defined as the convex conjugate of a generalized entropy penalty functional and an interpretation…
New DP algorithm improves privacy and efficiency for convex optimization.
problem Efficient, DP algorithms for convex optimization with strong excess risk bounds.
method Output perturbation for a broad class of tilted loss functions.
result Near optimal DP excess risk and runtime bounds for convex optimization.
In statistical learning theory, convex surrogates of the 0-1 loss are highly preferred because of the computational and theoretical virtues that convexity brings in. This is of more importance if we consider smooth surrogates as witnessed by the fact that the smoothness is further beneficial both computationally- by at…
The Lebesgue property (order-continuity) of a monotone convex function on a solid vector space of measurable functions is characterized in terms of (1) the weak inf-compactness of the conjugate function on the order-continuous dual space, (2) the attainment of the supremum in the dual representation by order-continuous…
Paper studies non-convex truncated loss functions for robust learning.
problem Improving generalization with non-convex loss functions.
method Truncating traditional loss functions and using SGD.
result Excess risk bounds and stationary points found by SGD.
The risk of financial positions is measured by the minimum amount of capital to raise and invest in eligible portfolios of traded assets in order to meet a prescribed acceptability constraint. We investigate nondegeneracy, finiteness and continuity properties of these risk measures with respect to multiple eligible ass…
Extends risk measure theory to general Orlicz spaces.
problem Applying risk measure theory to non-standard spaces.
method Generalizes results from bounded random variables to general Orlicz spaces, proving new characterizations and extensions.
result Characterizations and extensions of the Fatou property and Kusuoka representation in Orlicz spaces.
Develops a framework for modeling liquidity risk using convex risk measures.
problem Modeling liquidity risk using convex risk measures.
method Exploits concentration of measure techniques to bound liquidity risk profiles.
result Derives tractable necessary and sufficient conditions for concentration inequalities of liquidity risk profiles.
Geometric expectiles generalize expectiles for multivariate data.
problem Generalizing expectiles for multivariate distributions.
method Convex risk minimization problem solution for d-dimensional vectors.
result Geometric expectiles are consistent risk measures under common transformations.
The paper derives risk measures for metalog distributions.
problem Deriving risk measures for metalog distributions.
method Closed-form expressions for Conditional Value at Risk and first-order partial moments.
result First-order partial moments are convex with respect to metalog parameters.
New framework for robust hypothesis testing using Sinkhorn uncertainty sets.
problem Non-convex robust hypothesis testing problem.
method Exact mixed-integer exponential conic reformulation and convex approximation.
result Satisfactory testing performance and computational efficiency.
The paper explores non-convex risk measures and their characterizations.
problem Characterizing non-convex risk measures without convexity or weak convexity.
method Characterizes monetary risk measures as lower envelopes of families of convex or coherent risk measures, considering law-invariance and SSD-consistency.
result Unified representation theorems for law-invariant risk measures, including VaR.