>On 9/3/07,Vimal<[EMAIL PROTECTED]> wrote: >>while E do >>S >>if F then >>break >>end >>T >>end >> >>He then asked us to *prove* that the above programming fragment cannot >> >>be implemented just using if and while statement, even if S and T can >>be duplicated a finite number of times >But it IS possible. Just add a boolean flag:
Possibly, you are not allowed to change the sequence of machine operations at all. See, if you change "while(A){B}" to "if(A){B};while(A){B}", the sequence is exactly the same; but it's not possible in this case. It reminds me of a paper by Knuth, where he states that "goto" statement is necessary; don't remember the title, however. _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe