Suppose that L in C(x)[tau] is an irreducible operator.

The program AbsFactorization works by asking LREtoolsl[RightFactors] to compute
factors of order degree(L,tau)/p of the operator section_op(L, p).

Say an*tau^n + ... + a0*tau^0 is a potential right-factor, then (-1)^n * a0/an
is called its determinant. To find right-factors, the program RightFactors
constructs a list of "candidate determinants"  (the actual determinant
will be tau(P)/P times an element of this list, for some polynomial P).

The smaller the list of candidate-determinants is, the faster RightFactors will
run (because it means that there are fewer cases to check).

If we discard candidate-determinants that are not compatible with the original
operator L (the input of AbsFactorization) then RightFactors can run faster.

A similar improvement holds for the "candidate Newton polygon/polynomials"
of the potential right-factors.  Fewer candidates means fewer cases to check,
which means a better runtime.

The version of "AbsFactorization" in this file passes two pieces of data
to RightFactors:  One that contains "InvariantTerms(L)", which includes
all of the Newton-polygon/polynomials, but some additional terms as well
when the slope is not integer.  The other is the ReducedDeterminant of L
(the determinant up equivalence, where d1~d2 if d1/d2 = tau(f)/f for some
rational function f).

The file RightFactors.txt in this folder is nearly identical to LREtools[RightFactors]
except that if _Env_RightFactors_data is assigned, then it calls the programs
DetFactorsSelect and DeterminantSelect in the file Absolute_Factorization.txt
to trim the list of cases.


Note that if the number of cases was not very high to begin with, then the
improvement may be negligable. This is because RightFactors already discards
candidate-determinants that are not compatible with data coming from
GeneralizedExponents.

In order to see an improvement, we constructed an example L4 with a significant
number of cases, to be precise, if _Env_RightFactors_data is not assigned,
then RightFactors checks 1791 cases, and for each case, it computes polynomial
solutions of a "exterior power system".
The data in _Env_RightFactors_data reduced the number of cases to 121. This
example is included in the file Absolute_Factorization.txt