Matching Or expressions
- To: mathgroup at smc.vnet.net
- Subject: [mg72250] Matching Or expressions
- From: Johan Grönqvist <johan.gronqvist at gmail.com>
- Date: Sat, 16 Dec 2006 05:18:10 -0500 (EST)
The context of my problem is explained below.
I wish to distinguish expressions of the form And[p,q] from those of the
form Or[p,q], but the only thing I find is
and to my surprise I see that MatchQ[And[p,q],Or[_]] is True. Thus I can
not use this to match only the Or-expressions.
The context is as follows:
I wish to find the number of solutions to a diophantine equation with a
finite number of solutions.
I do the following
sols = Reduce[eqns, vars, Integers]
and this gives me an expression that normally looks like Or[_,_,_] if
there are several solutions, or something else if there are not.
Now I wish to find the number of solutions using
Which[MatchQ[sols, Or[_]], Length[sols], DoOtherStuff]
The problem is that the MatchQ[ expr, Or[_] ] also matches e.g. (x==2 &&
y==4), which is only one solution.
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