Criteria in order that a Musielak-Orlicz sequence space $l^\Phi$ contains an isomorphic as well as an isomorphically isometric copy of $l^1$ are given. Moreover, it is proved that if $\Phi = (\Phi_i)$, where $\Phi_i$ are defined on a Banach space, $X$ does not satisfy the $\delta^o_2$-condition, then the Musielak-Orlicz sequence space $l^\Phi (X)$ of $X$-valued sequences contains an almost isometric copy of $c_o$. In the case of $X = I\!\!R$ it is proved also that if $l^\Phi$ contains an isomorphic copy of $c_o$, then $\Phi$ does not satisfy the $\delta^o_2$-condition. These results extend some results of [A] and [H2] to Musielak-Orlicz sequence spaces.
@article{118636, author = {Ghassan Alherk and Henryk Hudzik}, title = {Copies of $l^1$ and $c\_o$ in Musielak-Orlicz sequence spaces}, journal = {Commentationes Mathematicae Universitatis Carolinae}, volume = {35}, year = {1994}, pages = {9-19}, zbl = {0820.46013}, mrnumber = {1292578}, language = {en}, url = {http://dml.mathdoc.fr/item/118636} }
Alherk, Ghassan; Hudzik, Henryk. Copies of $l^1$ and $c_o$ in Musielak-Orlicz sequence spaces. Commentationes Mathematicae Universitatis Carolinae, Tome 35 (1994) pp. 9-19. http://gdmltest.u-ga.fr/item/118636/
On the non-$l_n^{(1)}$ and locally uniformly non-$l_n^{(1)}$ properties and $l^1$ copies in Musielak-Orlicz space, Comment. Math. Univ. Carolinae 31 (1990), 435-443. (1990) | MR 1078478
Positive operators, Pure and Applied Math., Academic Press, Inc., 1985. | MR 0809372 | Zbl 1098.47001
On bases and unconditional convergence of series in Banach spaces, Studia Math. 17 (1958), 151-164. (1958) | MR 0115069
Uniformly non-$l^{(1)}_n$ Musielak-Orlicz sequence spaces, Proc. Indian Acad. Sci. 101 (1991), 71-86. (1991) | MR 1125480
On some equivalent conditions in Musielak-Orlicz spaces, Comment. Math. (Prace Matem.) 24 (1984), 57-64. (1984) | MR 0759055 | Zbl 0564.46022
Orlicz spaces containing a copy of $l^1$, Math. Japonica 34 (1989), 747-759. (1989) | MR 1022152
Support functionals and smoothness in Musielak-Orlicz sequence spaces endowed with the Luxemburg norm, Comment. Math. Univ. Carolinae 31 (1990), 661-684. (1990) | MR 1091364 | Zbl 0721.46012
Flat Orlicz-Musielak sequence spaces, Bull. Acad. Polon. Sci. Math. 30 (1982), 347-352. (1982) | MR 0707748
Functional Analysis (in Russian), Nauka, Moscow, 1977. | MR 0511615
Convex functions and Orlicz spaces, Groningen, 1961 (translation).
Banach function spaces, Thesis, Delft, 1955. | MR 0072440 | Zbl 0162.44701
Orlicz spaces and modular spaces, Lecture Notes in Math. 1034, SpringerVerlag, 1983. | MR 0724434 | Zbl 0557.46020
Theory of Orlicz spaces, Pure and Applied Mathematics, Marcel Dekker, 1991. | MR 1113700 | Zbl 0724.46032
Fenchel-Orlicz spaces, Dissertationes Math. 181 (1980), 1-60. (1980) | MR 0578390 | Zbl 0435.46025