This is an announcement for the paper "On compositions of d.c. functions and mappings" by L. Vesely and L. Zajicek. Abstract: A d.c. (delta-convex) function on a normed linear space is a function representable as a difference of two continuous convex functions. We show that an infinite dimensional analogue of Hartman's theorem on stability of d.c. functions under compositions does not hold in general. However, we prove that it holds in some interesting particular cases. Our main results about compositions are proved in the more general context of d.c. mappings between normed linear spaces. Archive classification: math.FA math.CA Mathematics Subject Classification: 46B99; 26B25; 52A41 Remarks: 19 pages The source file(s), PFzkr13.tex: 57750 bytes, is(are) stored in gzipped form as 0706.0624.gz with size 18kb. The corresponding postcript file has gzipped size 125kb. Submitted from: zajicek@karlin.mff.cuni.cz The paper may be downloaded from the archive by web browser from URL http://front.math.ucdavis.edu/0706.0624 or http://arXiv.org/abs/0706.0624 or by email in unzipped form by transmitting an empty message with subject line uget 0706.0624 or in gzipped form by using subject line get 0706.0624 to: math@arXiv.org.