• Bulletin of the Korean Mathematical Society
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• v.35 no.3
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• pp.409-420
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• 1998

In this paper as a univesal Banach space of the separable Banach spaces we investigate the complemented Banach subspaces of $_wL_{\hat {I}}$. Also, using Peck's theorem and the properties of the envelope norm of $_wL_{\hat {I}}$ we will find a canonical basis of $l_1^n, l_\infty^n$ for each n.

• Korean Journal of Mathematics
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• v.27 no.3
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• pp.645-655
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• 2019

In this article, we show that the nuclear operator defined on Banach space has an extending and lifting operator. Also we give new proofs of the well known facts which were given $Pelcz{\acute{y}}nski$ theorem for complemented subspaces of ${\ell}_1$ and Lewis and Stegall's theorem for complemented subspaces of $L_1({\mu})$.

• Communications of the Korean Mathematical Society
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• v.11 no.4
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• pp.1015-1030
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• 1996

We investigate complemented Banach subspaces of the Banach envelope of $eak L_1$. In particular, the Banach envelope of $weak L_1$ contains complemented Banach sublattices that are isometrically isomorphic to $l_p, (1 \leq p < \infty)$ or $c_0$. Finally, we also prove that the Banach envelope of $weak L_1$ contains an isomorphic copy of $l^{p, \infty}, (1 < p < \infty)$.