Sehie Park
The National Academy of Sciences, Republic of Korea, Seoul 06579; and
Department of Mathematical Sciences, Seoul National University, Seoul 08826, Korea
For a long period, the so-called L-structure or L-spaces have been studied by several authors. However, there exist several misconceptions, such as the belief that L-spaces extend the well-known generalized convex (G-convex) spaces. In order to clarify these misunderstandings, we demonstrate that KKM theory on abstract convex spaces improves typical results in L-spaces. The main topics in this paper relate to extensions of the Himmelberg fixed point theorem. Since such studies transcend the framework of L-spaces, we assert that it is time to abandon the unproductive study of L-spaces and their variants, FC-spaces.
Keywords: Abstract convex space, KKM theorem, multimap classes R,D, (partial) KKM space, fixed point theorem, L-space, FC-space.
Park, S. (2020). The rise and fall of L-spaces. Advances in the Theory of Nonlinear Analysis and its Application, 4(3), 152-166.