factor command call graph:

  rat:factor->sexp
    factors->sexp
      int:factor
        sexp:terms->product-of-powers
	sort! (slib)
	factor (slib)
      cano->sexp
      poly:sort-factors
        sort! poly:factor<
      factors-list->fact-exps
    int:factor ...
    poly:factorz
      poly:factorz ...
      prepend-integer-factor
      u:factorsz
        ff:berlekamp
          ff:generate-field
          ff:null-space-basis [KV2 4.6.2]
        hen:ulhenseln
          hen:diophantine  &  check-hd
            hen:univariate-diophant  &  check-hd1 [GCL 6.3 p 270]
              pairwise-relatively-prime?
              hen:multiterm-eea-lift  &  check-mel [GCL 6.3 p 271]
                hen:diophantine ...
              hen:eea-lift  &  check-ext-gcd
                ff:eea-gcd [GCL 2.2 p 36]
?       hen:ulhensel3
          hen:diophantine ...
?       hen:ulhensel2
          ff:eea-gcd ...
      map-svpf-factors
        yuniv:square-free-factorization [GCL 8.2 p 342]
        poly:factorszpp
          poly:factorz ...
          u:factorsz ...
          yuniv:square-free-factorization ...
          hen:multivariate-hensel [GCL 6.4 p 272]
            taylor-coefficient
            pairwise-relatively-prime? ...
            hen:univariate-diophant ...
            hen:multivariate-diophant  &  check-hd1 [GCL 6.2 p 268]
              hen:multivariate-diophant ...
              taylor-coefficient ...
              pairwise-relatively-prime? ...
  rat:factors
    poly:sort-merge-factors
      poly:sort-factors ...
    negate-factors-exps
    poly:factorz ...

? = using hen:ulhenseln instead does not affect operations
... occured previously in graph
[GCL x.x] refers to algorithm numbers in:
  Algorithms for Computer Algebra
  by Keith O. Geddes, Stephen R. Czapor, George Labahn
  (October 1992) Kluwer Academic Pub; ISBN: 0-7923-9259-0
[KV2 4.6.2] refers to algorithm in:
  The Art of Computer Programming : Seminumerical Algorithms (Vol 2)
  by Donald Ervin Knuth
  2nd Ed (1981) Addison-Wesley Pub Co; ISBN: 0-201-03822-6
