Algorithms for Risk Mitigation in Networks
summary
Uncertainty forces new algorithms: minimizing a mean+standard-deviation objective is nonadditive so optimal substructure fails, but projecting paths to the mean–variance plane reduces the search to extreme points and yields an exact enumeration algorithm with a worst-case n^{log n} extreme-point bound. Smoothed analysis and an MIT Kartel implementation report about 10 extreme points in Boston (Kartel), and a black-box reduction to deterministic shortest-path solvers gives practical (1+ε) approximations. Game-theoretically, the price of risk aversion can grow like 1+R·K (times a topology factor up to V/2).
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chapters (27)
- 0:00Intro
- 0:27Motivation
- 2:10Talk outline
- 2:40What is risk?
- 4:32Risk l: Expected Utility Theory
- 5:57Risk Il: Mean-variance framework
- 9:31Risk III: Coherent risk measures
- 12:37Computational implications
- 16:19Algorithmic challenges
- 18:57Algorithmic insights
- 31:57Risk-averse combinatorial framework
- 34:17General utility functions
- 35:26Traffic routing
- 36:45Risk sensitivity of price of anarchy
- 37:54Related work on routing games
- 38:06Goal
- 39:29Routing games with stochastic delays
- 41:57Risk-averse vs Risk-neutral Wardrop Equilibrium
- 42:59Equilibrium characterization for mean-stdev risk
- 43:31Succinct Solution Representation
- 44:35Effect of Risk vs Selfish Behavior?
- 46:56Risk-averse vs Risk-neutral equilibria
- 49:09Price of Risk Aversion for mean-var risk
- 51:14Dynamic (adaptive) problems
- 51:33Summary
- 52:58Open/Future research directions
- 57:28Heterogeneous risk-averse players
