Abstract
The problem of the estimation of a regression function by continuous piecewise linear functions is formulated as a nonconvex, nonsmooth optimization problem. Estimates are defined by minimization of the empirical L 2 risk over a class of functions, which are defined as maxima of minima of linear functions. An algorithm for finding continuous piecewise linear functions is presented. We observe that the objective function in the optimization problem is semismooth, quasidifferentiable and piecewise partially separable. The use of these properties allow us to design an efficient algorithm for approximation of subgradients of the objective function and to apply the discrete gradient method for its minimization. We present computational results with some simulated data and compare the new estimator with a number of existing ones.
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Bagirov, A.M.: Minimization methods for one class of nonsmooth functions and calculation of semi-equilibrium prices. In: Eberhard, A., et al. (eds.) Progress in Optimization: Contribution from Australia, pp. 147–175. Kluwer Academic, Dordrecht (1999)
Bagirov, A.M., Ugon, J.: Piecewise partially separable functions and a derivative-free method for large-scale nonsmooth optimization. J. Glob. Optim. 35, 163–195 (2006)
Bagirov, A.M., Ghosh, M., Webb, D.: A derivative-free method for linearly constrained nonsmooth optimization. J. Ind. Manag. Optim. 2(3), 319–338 (2006)
Bagirov, A.M., Karasozen, B., Sezer, M.: Discrete gradient method: a derivative free method for nonsmooth optimization. J. Optim. Theory Appl. (2008). DOI: 10.1007/s10957-007-9335-5
Bartels, S.G., Kuntz, L., Sholtes, S.: Continuous selections of linear functions and nonsmooth critical point theory. Nonlinear Anal. TMA 24, 385–407 (1995)
Breiman, L., Friedman, J.H., Olshen, R.H., Stone, C.J.: Classification and Regression Trees. Wadsworth, Belmont (1984)
Clarke, F.H.: Generalized gradients and applications. Trans. Am. Math. Soc. 205, 247–262 (1975)
Clarke, F.H.: Optimization and Nonsmooth Analysis. Wiley, New York (1983)
Demyanov, V.F., Rubinov, A.M.: Constructive Nonsmooth Analysis. Peter Lang, Frankfurt am Main (1995)
Friedman, J.H.: Multivariate adaptive regression splines (with discussion). Ann. Stat. 19, 1–141 (1991)
Gorokhovik, V.V., Zorko, O.I., Birkhoff, G.: Piecewise affine functions and polyhedral sets. Optimization 31(3), 209–221 (1994)
Györfi, L., Kohler, M., Krzyżak, A., Walk, H.: A Distribution-Free Theory of Nonparametric Regression. Springer Series in Statistics. Springer, Heldelberg (2002)
Hastie, T., Tibshirani, R., Friedman, J.: The Elements of Statistical Learning. Springer, New York (2001)
Mifflin, R.: Semismooth and semiconvex functions in constrained optimization. SIAM J. Control Optim. 15, 957–972 (1977)
The R Project for Statistical Computing. Available on: www.r-project.org
Wolfe, P.H.: Finding the nearest point in a polytope. Math. Program. 11, 128–149 (1976)
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Bagirov, A., Clausen, C. & Kohler, M. An algorithm for the estimation of a regression function by continuous piecewise linear functions. Comput Optim Appl 45, 159–179 (2010). https://doi.org/10.1007/s10589-008-9174-9
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DOI: https://doi.org/10.1007/s10589-008-9174-9