Title : Optimization by Vector Space Methods Abstract: Optimization theory , which is a branch of applied mathematics, looks to various areas of pure mathematics for its unification, clarification and general foundation. One such area of particular relevance is functional analysis. Functional analysis is the study of vector spaces of resulting from a merging of geometry, linear algebra and analysis. It serves as a basis for Fourier series, integral and differential equations, numerical analysis, and any field where linearity plays a key role. Its appeal as a unifying discipline stems primarily from its geometric character. This talk will focus on the some aspects of optimization theory which are derived from a few simple, intuitive, geometric insights. The conceptual utility of functional analysis will be motivated by showing how it enables us to extend our three-dimensional geometric insights to complex infinite-dimensional problems. The projection theorem will be used as the motivating example. In ordinary three-dimensional space, it states that the shortest line from a point to a plane is furnished by the perpendicular from the point to the plane. This result has direct extensions in spaces of higher dimension and in infinite-dimensional Hilbert space. If time permits, I will also show how the Hahn-Banach theorem serves as an appropriate generalization of the projection theorem from Hilbert spaces to arbitrary normed spaces.