RegularChains[ChainTools]
SquarefreeFactorization
compute a square-free decomposition of a polynomial modulo a regular chain
Calling Sequence
Parameters
Description
Examples
Compatibility
SquarefreeFactorization(p, v, rc, R)
SquarefreeFactorization(p, v, rc, R,options)
p
-
polynomial
v
variable
rc
regular chain
R
polynomial ring
options
equation of the form 'method'=mth, where mth is either 'evala' or 'src'
The command SquarefreeFactorization(p, v, rc, R) returns a list of pairs [sqf_i, rc_i]. For each pair, the list sqf_i is a square-free decomposition of p modulo the saturated ideal of rc_i; each element in the list sqf_i is a pair as [s_j,e_j], where s_j is a square-free polynomial modulo rc_i and e_j is the exponent of s_j in p.
All the regular chains from the output pairs form a triangular decomposition of rc in the sense of Kalkbrener.
The option 'method' specifies which gcd algorithm to use. The default option, 'method'='evala', uses a modular algorithm. The other option is 'method'='src', which uses a subresultant-based approach. This method is generally slower, but can be faster in some cases, for instance, if the dimension of the saturated ideal of rc is high, say greater than 4.
Assumptions: the polynomial ring is assumed to have characteristic zero; the initial of p is regular w.r.t. rc; v is greater than the main variables of the regular chain rc in R.
Example 1
with⁡RegularChains:with⁡ChainTools:
R≔PolynomialRing⁡y,x
R≔polynomial_ring
q≔expand⁡x−22⁢x−12
q≔x4−6⁢x3+13⁢x2−12⁢x+4
p≔prem⁡y+6⁢y+2−x⁢x⁢y2−1⁢y−x,q,x
p≔x3⁢y3−2⁢x2⁢y4+x⁢y5+6⁢x3⁢y2−14⁢x2⁢y3+8⁢x⁢y4−12⁢x2⁢y2+12⁢x⁢y3−x2⁢y+2⁢x⁢y2−y3−6⁢x2+14⁢y⁢x−8⁢y2+12⁢x−12⁢y
C≔Chain⁡q,Empty⁡R,R
C≔regular_chain
SquarefreeFactorization⁡p,y,C,R
2⁢y5+8⁢y4−25⁢y3−4⁢y2+12⁢y,1,regular_chain,y+6,1,y2−1,2,regular_chain
SquarefreeFactorization⁡p,y,C,R,method=src
Example 2
R≔PolynomialRing⁡x,y
p≔x+y⁢x+2⁢y2⁢x+3⁢y3
rc≔Chain⁡y2+1,Empty⁡R,R
rc≔regular_chain
p≔SparsePseudoRemainder⁡p,rc,R
p≔x6+14⁢x5⁢y−80⁢x4−238⁢x3⁢y+387⁢x2+324⁢x⁢y−108
SquarefreeFactorization⁡p,x,rc,R
x+y,1,x+2⁢y,2,x+3⁢y,3,rc
Example 3
rc≔Chain⁡y2+y,Empty⁡R,R
p≔x6+14⁢x5⁢y−80⁢x4⁢y+238⁢x3⁢y−387⁢x2⁢y+324⁢x⁢y−108⁢y
x−1,1,x−2,2,x−3,3,regular_chain,x,6,regular_chain
SquarefreeFactorization⁡p,x,rc,R,method=src
The RegularChains[ChainTools][SquarefreeFactorization] command was introduced in Maple 16.
For more information on Maple 16 changes, see Updates in Maple 16.
See Also
gcd
RegularGcd
RegularizeInitial
Squarefree
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