Пусть $M=\langle M, <, \ldots\rangle$ --- линейно упорядоченная
структура. Подмножество $B$ структуры $M$ называется {\it выпуклым,}
если всякий раз когда $a 1. A.~Pillay, C.~Steinhorn, {\it ``Definable sets in ordered
structures I''}, {\bf Trans\-ac\-tions of the American Mathematical Society},
295 (1986), pp. 565--592.\\
2. В.S.~Baizhanov, {\it ``Classification of one-types in
weakly \mbox{o-mi}\-nimal theories and its corollaries''}, {\bf The Journal of
Sym\-bo\-lic Logic}, 1997 (submitted).\\
3. B.Sh.~Kulpeshov, {\it Some properties of $\aleph$--categorical weakly o-minimal
theories}, {\bf Algebra and Model Theory} (A.G.~Pinus and
K.N.~Ponomaryov, editors), Novosibirsk, 1997, pp. 78-98.