(no subject)

David Feuer David_Feuer@brown.edu
Mon, 10 Dec 2001 19:17:43 -0500


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