15.1 Bifurcation Methods 15.2 Portfolio Choices for Small Risks 15.3 Gauge Functions and Asymptotic Expansions 15.4 Method of Undetermined Gauges 15.5 Asympotic Expansions of Integrals 15.6 Hybrid Perturbation-Projection Methods 15.7 Further Reading and Summary 15.8 Exercises