uma kompella wrote:

hi

i am new to haskell and am having a problem to write function which takes a boolean expression and returns a truthvalue stating whether or not it is a tautology.

Can anyone please help me??

Thanks a lot uma

I assume this is your homework. It is better to say so explicitly. Think about this: what does it mean for an expression to be a tautology? Can you think of an a way to check this? Once you've come up with a way to check this, it should be quite easy to write it in Haskell. -- /Times-Bold 40 selectfont/n{moveto}def/m{gsave true charpath clip 72 400 n 300 -4 1{dup 160 300 3 -1 roll 0 360 arc 300 div 1 1 sethsbcolor fill}for grestore 0 -60 rmoveto}def 72 500 n(This message has been)m (brought to you by the)m(letter alpha and the number pi.)m(David Feuer) m(David_Feuer@brown.edu)m showpage