What if you don't understand the st

What if you don't understand the statement? If there's a symbol in the
formula you don't understand, perhaps a ±;look to see whether the next line
continues, where±is such and such." In other words, read the whole sentence
before you decide you can't understand it. In this book we have tried to de¯ne
all terms before giving formulas, but we may not have succeeded everywhere.