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 MatchQ[myExpr, Or[_]] 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. Thanks Johan 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.

**Follow-Ups**:**Re: Matching Or expressions***From:*Andrzej Kozlowski <akoz@mimuw.edu.pl>