I meant that if you want your language to be unambiguous in what tree it produces, you have to choose (somehow not be ambiguous). You can be explicit in your gr

I meant that if you want your language to be unambiguous in what tree it produces, you have to choose (somehow not be ambiguous). You can be explicit in your grammar and semantics of your grammar, or you could throw away some set of "wrong" trees - or you can be implicit - allow your grammar (under certain semantic assumptions be ambiguous) - and assume left /right. But if the grammar and semantics allow (force) you to be explicit - I'm not sure I see it as a problem. I certainly see how allowing ambiguity with a warning/error would also be good. I'm on a cellphone now, and can't see if I can make useful/surprising grammar for the a/aa|a/aaa languages in ohm. Maybe it's just too minimal an example for me (why not: a|aaa or aa+ - or whatever one is trying to express? Is it, say about the language of pairs or triplets of "a"s?).