Core Concepts
An effective method for primary decomposition of symmetric ideals by utilizing the symmetric structure of the ideals.
Abstract
The paper proposes an effective algorithm for primary decomposition of symmetric ideals. The key insights are:
Primary decomposition of a symmetric ideal has a symmetric structure - if {Q1, ..., Qk} is a minimal primary decomposition of a symmetric ideal I, then {σ(Q1), ..., σ(Qk)} is also a minimal primary decomposition of I for any permutation σ in the symmetric group Sn.
To handle the non-uniqueness of primary decompositions, the authors introduce the concept of "the quotient set of primary components" of I, which is uniquely determined from I. They show that the symmetric group Sn acts on this quotient set.
The authors devise an effective algorithm for computing the primary decomposition of a symmetric ideal by leveraging the symmetric structure. The algorithm only needs to compute a partial set of primary components and can derive the full primary decomposition from them using the group action.
The authors also provide practical improvements to the algorithm by specializing the Shimoyama-Yokoyama algorithm for symmetric ideals. This includes computing a symmetric system of separators and a symmetric saturated separating ideal.
Experiments show that the specialized symmetric algorithm outperforms the general primary decomposition algorithm, especially for ideals with many primary components and high symmetry.