Achieving pole-law inflation: the extreme inflation

The pre-big bangʹs inflationary mechanism, when allowance is made for the rapid changing of Newtonʹs constant, is not actually of pole-law form. We give examples where pole-law inflation, which requires violation of the weak-energy condition, is possible but unlikely due to its very unstable character. Comparisons are made with conventional inflation which only violates the strong-energy condition.