## issue with p_Deg() for lexicographical ordering?

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 issue with p_Deg() for lexicographical ordering? Jakob Kroeker 6/27/16 3:49 PM Consider the following example:`ring rng = 0,(x,y), lp;poly p = x;deg(x);`when I use p_Deg() to compute the degree of x instead of pLDeg(),  I get `65536 as an answer. Is it not allowed to use p_Deg() for lexicographical orderingsor is it a bug?` Re: [libsingular-devel] issue with p_Deg() for lexicographical ordering? han...@mathematik.uni-kl.de 6/28/16 1:22 AM On Mon, Jun 27, 2016 at 03:49:50PM -0700, Jakob Kroeker wrote: >    Consider the following example: > >    ring rng =  0,(x,y), lp; >    poly p = x; >    deg(x); >    when I use p_Deg() to compute the degree of x instead of pLDeg(),A  I get > >  65536 as an answer. > > >  Is it not allowed to use p_Deg() for lexicographical orderings >  or is it a bug? A degree function is a map d: monomials -> integers>=0 which has the properties: - d(1) = 0 - d(f*g) = d(f) + d(g) - if f > g then d(f) >= d(g) Examples for degree functions are: - p_Deg - p_Totaldegree - p_WTotaldegree (only for orderings with weights != 1) To ease the choice for the different orderings there are function pointers pointing to the most useful degree function for the ring given: - p_FDeg for the degree of the leading monomial - p_LDeg for the maximal degree of all monomials of the polynomials The answers to your questions: - no, it is allowed to use p_Deg, but it may return correct but   surprising results for block orderings - no, it is not a bug Suggestion: use p_FDeg or p_Totaldegree Hannes