( x+y = z )

( {x+y = z} )

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Here is an example formula ( x+y = z ) which we repeat at several
times during the paragraph.  Notice that the spacing changes on
different uses ( x+y = z ) depending on how much the line is
stretch.  This is useful as it helps with even spacing of the whole
paragraph despite the presence of formulae ( x+y = z ).  Stretchable
spacing in the mathematics ( x+y = z ) is often to be preferred.

Using braces verb!{}! around the forumla ( {x+y = z} ) freezes the
spacing.  It also prevents line breaks occuring in the middle of the
formula ( {x+y = z} ).  This prevention of line breaks can also be
used in subformals, but we are demonstrating that in the case of (
{x+y = z} ).  I expect to see that the spacing in this paragraph is
not as good as the previous because of the lack of flexibility
associated to the formula ( {x+y = z} ).

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