Let XX be a Banach space. Using derivatives in the sense of vector distributions, we show that the space DC([0,1],X)DC([0,1],X) of all d.c. mappings from [0,1][0,1] into XX, in a natural norm, is isomorphic to the space Mbv([0,1],X)M_{bv}([0,1], X) of all vector measures with bounded variation. The same is proved for the space BDCb((0,∞),X)BDC_b((0,\infty), X) of all bounded d.c. mappings with a bounded control function. The result for the space DC([0,1],R)DC([0,1], \R) of all continuous d.c. functions was (essentially) proved by M. Zippin [The space of differences of convex functions on [0,1][0,1], Serdica Math. J. 26 (2000) 331–352] by a quite different method. The space BDCb((0,∞),R)BDC_b((0,\infty), \R) consists of all differences of two bounded convex functions. Internal characterizations of its members were given by O. B{ö}hme [On functions which are the difference of two bounded convex functions on (0,∞)(0,\infty), Math. Nachr. 122 (1985) 45–58], but our characterization of its Banach structure is new.

Contact details are reproduced from the original publication and may be historical.

Libor Veselý

Università degli Studi di Milano, Dip. di Matematica "F. Enriques", Via C. Saldini 50, 20133 Milano, Italy

libor.vesely@unimi.it

Luděk Zajíček

Faculty of Mathematics and Physics, Charles University, Sokolovská 83, 18675 Praha 8, Czech Republic

zajicek@karlin.mff.cuni.cz
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L. Veselý, L. Zajíček. “Spaces of d.c. Mappings on Arbitrary Intervals.” Journal of Convex Analysis 23 (2016), No. 4, 1161–1183. https://doi.org/10.68381/jca23043