You're right, Gregg, you did avoid the reversible assignment topic.
Although I do not know how to utilize Icon's built-in features to generate all possible combinations/permutations (which one is it?) where the letters appear once and only once, I do believe that, given the generated list, I will recognize the valid words. And I'm sure that Icon can EASILY produce the list, whether the algorthim utilizes reversible assignment or not. Can someone show me how?