2009/3/31 john skaller <skal...@users.sourceforge.net> > > On 01/04/2009, at 12:52 AM, Emmanuel Onzon wrote: > > >> Suppose you have + < ^ (addition less than >> exponentiation) and you want to add multiplication: >> >> + < * >> * < ^ >> >> then since Dypgen relations are not transitive you have to *remove* the >> relation >> >> + < ^ >> >> to build a strict chain. >> >> No you don't have to remove it. Making a relations transitive >> is not mandatory but it is not forbidden either. >> You can even introduce the transitive closure of the relation >> for a list of priorities with: >> Relation [["p1";"p2";"p3";"p4"]] >> >> If you remove + < ^ then you lose the precedence >> of ^ over + and the expression: >> >> a ^ b + c >> >> become ambiguous. >> > > Exactly what is desired by a "strict chain". Here you wish > to force the user to write > > (a ^ b) + c > > i..e. to put brackets in. Example is artificial though :) >
So you mean: if there is a precedence between two already existing operators (say ^ and +) then when adding a new operator (say *) the precedence between the first two operators should disappear ? I don't understand why this behavior is better than keeping the precedence. The user can still use the parenthesis if he means something different. If you want to force the user to use parenthesis, why using precedences (and priorities) at all?
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