We describe new algorithms for determining the adjacencies between zero-dimensional cells and those one-dimensional cells that are sections (not sectors) in cylindrical algebraic decompositions (cad). Such adjacencies constitute a basis for determining all other cell adjacencies. Our new algorithms
Algorithms in Local Algebra
✍ Scribed by Hans-Gert Gräbe
- Publisher
- Elsevier Science
- Year
- 1995
- Tongue
- English
- Weight
- 395 KB
- Volume
- 19
- Category
- Article
- ISSN
- 0747-7171
No coin nor oath required. For personal study only.
✦ Synopsis
Let (k) be a field, (S=k\left[x_{v}: v \in V\right]) be the polynomial ring over the finite set of variables ( (x_{v}: v \in V) ), and (m=\left(x_{v}: v \in V\right)) the ideal defining the origin of Spec S.
It is theoretically known (see e.g. Alonso et al., 1991) that the algorithmic ideas for the computation of ideal (and module) intersections, quotients, deciding radical membership etc. in (S) may be adopted not only for computations in the local ring (S_{m}) but also for term orders of mixed type with standard bases replacing Gröbner bases. Using the generalization of Mora's tangent cone algorithm to arbitrary term orders we give a detailed description of the necessary modifications and restrictions.
In a second part we discuss a generalization of the deformation argument for standard bases and independent sets to term orders of mixed type. For local term orders these questions were investigated in Gräbe (1991).
The main algorithmic ideas described are implemented in the author's REDUCE package CALI (Gräbe , 1993a).
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