CHARACTERIZATION OF THE DUAL SPACE OF L1 AND
LEBESGUE DECOMPOSITION FOR NON-σ-FINITE
MEASURE SPACES
Abstract. The purpose of this paper is to determine the dual space of the space $\cL$ of all Daniell integrable functions and to prove the Lebesgue decomposition theorem in general measure spaces. In the measure theory, it is well known that the dual space $(L^1)^*$ can be identified with essentially bounded function space $L^{\infty}=L^{\infty} (\Omega, \Sigma, \mu)$ when $\mu$ is $\sg$-finite, and that the non-$\sg$-finite measure $\mu$ fails the Lebesgue decomposition. We show, in general, that the element of $(L^1)^{*}$ consists of a particular family of measurable functions. We call this family ``folder'', and the folder enables us to determine the dual space of $L^1$ and to formulate the general Lebesgue decomposition theorem.
AMS Subject classification: 28B99, 46B22


Download full article from here (pdf format).

DOI: 10.12732/ijam.v26i5.8

Volume: 26
Issue: 5
Year: 2013