User blog comment:Hyp cos/R function II/@comment-2033667-20150407161050/@comment-2033667-20150407161615

So if I have it correctly:


 * {0+1}0 is well-formed
 * {0+1}{0+1}0 is not well-formed because the first {0+1} is a separator, and it is not immediately followed by a nonseparator or numeric term
 * {0{0+1}0+1}0 is well-formed
 * {0+1}{0+0} is well-formed
 * 0 is well-formed