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System of parameters

In mathematics, a system of parameters for a local Noetherian ring of Krull dimension d with maximal ideal m is a set of elements x<sub>1</sub>, ..., x<sub>d</sub> that satisfies any of the following equivalent conditions:

  1. m is a minimal prime over (x<sub>1</sub>, ..., x<sub>d</sub>).
  2. The radical of (x<sub>1</sub>, ..., x<sub>d</sub>) is m.
  3. Some power of m is contained in (x<sub>1</sub>, ..., x<sub>d</sub>).
  4. (x<sub>1</sub>, ..., x<sub>d</sub>) is m-primary.
  5. R/(x<sub>1</sub>, ..., x<sub>d</sub>) is an Artinian ring.

Every local Noetherian ring admits a system of parameters.

It is not possible for fewer than d elements to generate an ideal whose radical is m because then the dimension of R would be less than d.

If M is a k-dimensional module over a local ring, then x<sub>1</sub>, ..., x<sub>k</sub> is a system of parameters for M if the length of is finite.

General references

References