We present proofs, based on the Shapley-Folkman theorem, of the convexity of the range of a strongly continuous, finitely additive easure, as well as that of an atomless, countably additive measure. We also present proofs, based on diagonalization and separation arguments respectively, of the...

Shapiro-Shapley introduce their 1961 memorandum (published 17 years later as Shapiro-Shapley (1978)) with the remark that \institutions having a large number of competing participants are common in political and economic life, and cite as examples \markets, exchanges, corporations (from the...

For market with an atomless continuum of assets, we formulate the intuitive idea of a well-diversified portfolio, and present a notion of exact arbitrage, strictly weaker than the more conventional notion of asymptotic arbitrage, and necessary and sufficient for the validity of an APT pricing...

We provide a detailed portfolio analysis for a financial market with an atomless continuum of assets. In the context of an exact arbitrage pricing theory (EAPT), we go beyond the characterization of the existence of important portfolios (normalized riskless, mean, cost, factor and mean-variance...

This paper offers a sufficient condition, based on Maharam (1942) and re-emphasized by Hoover-Keisler (1984), for the validity of Lyapunov's (1940) theorem on the range of an atomless vector measure taking values in an infinite-dimensional Banach space that is not necessarily separable nor has...