setContainsVar :: Int -> Equations -> Bool
setContainsVar v = any (equationContainsVar v)
    where equationContainsVar :: Int -> Equation -> Bool
          equationContainsVar v (t,t') = (containsVar v t) || (containsVar v t')
setContainsVar :: Int -> Equations -> Bool
setContainsVar v = any (equationContainsVar v)
    where equationContainsVar :: Int -> Equation -> Bool
          equationContainsVar v (t,t') = (containsVar v t) || (containsVar v t')
setContainsVar v = any (equationContainsVar v)
    where equationContainsVar :: Int -> Equation -> Bool
          equationContainsVar v (t,t') = (containsVar v t) || (containsVar v t')