# The “dotplus” $\dotplus$ sign

Any one know what does the dot plus sign $\dotplus$ means? It is used to express a Hilbert space $H= \operatorname{span} \{f\} \dotplus V$, where $V$ is a Hilbert space, and $f$ is an analytic function.

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Often, dots indicate that the sum/union/etc is disjoint. Does this make sense in your context? – Phira Dec 5 '11 at 21:21
@Phira: Is $f(z)=\cos z$ of exponential type (at most) $\pi$? if no then your argument make since in my context! but I don't know about general case. – Katie Ml Dec 5 '11 at 21:24