Interval notation and Piecewise defined functions

[JDoolin]

I would like to present interval notation in openoffice math such as

x in (- infty, -5] union [5, infty)

However, because the brackets do not match, this is not allowed. I

Is there any workaround?

This situation also might come up in piecewise defined functions,

f(x) = left lbrace matrix{x^2+1, # x<0 ## x - 1, # x>=0} right rbrace

I would like to find a way to show only the left brace, but not the one on the right.

[Robert Tucker]

How about:

x in \(- infty, -5\] union \[5, infty\)

To have just a left brace use: right none

f(x) = left lbrace matrix{x^2+1, # x<0 ## x - 1, # x>=0} right none
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