Let $\Cal A$ be an algebra and $\Cal K$ a lattice of subsets of a set $X$. We show that every content on $\Cal A$ that can be approximated by $\Cal K$ in the sense of Marczewski has an extremal extension to a $\Cal K$-regular content on the algebra generated by $\Cal A$ and $\Cal K$. Under an additional assumption, we can also prove the existence of extremal regular measure extensions.
@article{118749, author = {Wolfgang Adamski}, title = {On the extremality of regular extensions of contents and measures}, journal = {Commentationes Mathematicae Universitatis Carolinae}, volume = {36}, year = {1995}, pages = {213-218}, zbl = {0834.28001}, mrnumber = {1357522}, language = {en}, url = {http://dml.mathdoc.fr/item/118749} }
Adamski, Wolfgang. On the extremality of regular extensions of contents and measures. Commentationes Mathematicae Universitatis Carolinae, Tome 36 (1995) pp. 213-218. http://gdmltest.u-ga.fr/item/118749/
On regular extensions of contents and measures, J. Math. Anal. Appl. 127 (1987), 211-225. (1987) | MR 0904223 | Zbl 0644.28002
On extremal extensions of regular contents and measures, Proc. Amer. Math. Soc. 121 (1994), 1159-1164. (1994) | MR 1204367 | Zbl 0817.28002
On the extremality of measure extensions, Manuscripta Math. 63 (1989), 89-97. (1989) | MR 0975471 | Zbl 0663.28004
Measures admitting extremal extensions, Arch. Math. 49 (1987), 257-266. (1987) | MR 0906740 | Zbl 0612.28002
Components in vector lattices and extreme extensions of quasi-measures and measures, Glasgow Math. J. 35 (1993), 153-162. (1993) | MR 1220557 | Zbl 0786.28002
Extensions of measure, Fund. Math. 36 (1949), 267-276. (1949) | MR 0035327 | Zbl 0039.05202
On compact measures, Fund. Math. 40 (1953), 113-124. (1953) | MR 0059994 | Zbl 0052.04902
Compact systems of sets, Lecture Notes in Math., Vol. 16, SpringerVerlag, 1966. | MR 0216529 | Zbl 0161.36604
Extremal and monogenic additive set functions, Proc. Amer. Math. Soc. 54 (1976), 193-196. (1976) | MR 0419711 | Zbl 0285.28005
Radon measures on arbitrary topological spaces and cylindrical measures, Oxford UP, 1973. | MR 0426084 | Zbl 0298.28001
Remark on extremal measure extensions, Lecture Notes in Math., Vol. 794, Springer-Verlag, 1980. | MR 0577962