This is an announcement for the paper "Contractively complemented subspaces of pre-symmetric spaces" by Matthew Neal and Bernard Russo.

Abstract: In 1965, Ron Douglas proved that if $X$ is a closed subspace of an $L^1$-space and $X$ is isometric to another $L^1$-space, then $X$ is the range of a contractive projection on the containing $L^1$-space. In 1977 Arazy-Friedman showed that if a subspace $X$ of $C_1$ is isometric to another $C_1$-space (possibly finite dimensional), then there is a contractive projection of $C_1$ onto $X$. In 1993 Kirchberg proved that if a subspace $X$ of the predual of a von Neumann algebra $M$ is isometric to the predual of another von Neumann algebra, then there is a contractive projection of the predual of $M$ onto $X$. We widen significantly the scope of these results by showing that if a subspace $X$ of the predual of a $JBW^*$-triple $A$ is isometric to the predual of another $JBW^*$-triple $B$, then there is a contractive projection on the predual of $A$ with range $X$, as long as $B$ does not have a direct summand which is isometric to a space of the form $L^\infty(\Omega,H)$, where $H$ is a Hilbert space of dimension at least two. The result is false without this restriction on $B$.

Archive classification: math.OA math.FA

Mathematics Subject Classification: 46B04,46L70,17C65

Remarks: 25 pages

The source file(s), ngoz020508.tex: 97855 bytes, is(are) stored in gzipped form as 0802.0734.gz with size 29kb. The corresponding postcript file has gzipped size 155kb.

Submitted from: brusso@math.uci.edu

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