© 1978 by Institute of Mathematics and its Applications
Dual Extremum Principles for Non-negative Unsymmetric Operators
National University of Mexico
Department of Mathematics, University of Reading
Dual extremum principles are constructed for non-negative unsymmetric operator equations. The theory is in terms of functional-valued linear operators defined on an infinite-dimensional space which need not even be normed. Saddle operators and saddle functional are constructed as essential ingredients. An extension to affine sub-spaces required for certain partial differential equations is included. New dual extremum principles for versions of the heat equation and the wave equation are stated in illustration.