A Projection-Based Algorithm for Consistent and Inconsistent Constraints

  • Authors:
  • Tuvia Kotzer;Nir Cohen;Joseph Shamir

  • Affiliations:
  • -;-;-

  • Venue:
  • SIAM Journal on Optimization
  • Year:
  • 1997

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Abstract

Signal synthesis and reconstruction is considered when the signal is to be determined by N constraint sets, Ci. The solution sought is required to minimize a weighted quadratic cost functional $\hat J$. Emphasis is on cases in which the intersection of the sets Ci is empty. Our proposed procedure employs a suitably weighted simultaneous projection iteration method. It is shown that the iterates generated by the algorithm converge weakly to a global minimizer of $\hat J$ provided the set of fixed points of the algorithm is nonempty. If the problem is consistent $(C_o:=\bigcap C_i \neq \emptyset),$ weak convergence is to an element in Co. However, it is indicated that large classes of inconsistent problems, which could not be treated by existing methods, admit a solution as well.