Roger Behling: On the Centralization of the Circumcentered-Reflection Method

Vortragende/Speaker: Prof. Dr. Roger Behling, Brazil, UFSC (Federal University of Santa Catarina) and FGV (Getulio Vargas Foundation)
Ansprechpartner/Contact: Prof. Dr. Andreas Fischer
Videostream (BBB): (on request)

Titel/Title:
On the Centralization of the Circumcentered-Reflection Method

Abstract/Zusammenfassung:
In this talk, we present the first circumcenter iteration scheme that does not employ a product space reformulation for finding a point in the intersection of two closed convex sets. We introduce a so-called centralized version of the circumcentered-reflection method (CRM). Developed with the aim of accelerating classical projection algorithms, CRM is successful for tracking a common point of a finite number of affine sets. In the case of general convex sets, CRM was shown to possibly diverge if Pierra’s product space reformulation is not used. In this work, we prove that there exists an easily reachable region consisting of what we refer to as centralized points, where pure circumcenter steps possess properties yielding convergence. The resulting algorithm is called centralized CRM (cCRM). In addition to having global convergence, cCRM converges linearly under an error bound condition, and superlinearly if the two target sets are so that their intersection have nonempty interior and their boundaries are locally differentiable manifolds. We also present numerical experiments with successful results.