Jacobson's conjecture

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In abstract algebra, Jacobson's conjecture is an open problem in ring theory concerning the intersection of powers of the Jacobson radical of a Noetherian ring.

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It has only been proven for special types of Noetherian rings, so far. Examples exist to show that the conjecture can fail when the ring is not Noetherian on a side, so it is absolutely necessary for the ring to be two-sided Noetherian.

The conjecture is named for the algebraist Nathan Jacobson who posed the first version of the conjecture.

Statement

For a ring R with Jacobson radical J, the nonnegative powers are defined by using the product of ideals.

Jacobson's conjecture: In a right-and-left Noetherian ring,

In other words: "The only element of a Noetherian ring in all powers of J is 0."

The original conjecture posed by Jacobson in 1956 [1] asked about noncommutative one-sided Noetherian rings, however Israel Nathan Herstein produced a counterexample in 1965, [2] and soon afterwards, Arun Vinayak Jategaonkar produced a different example which was a left principal ideal domain. [3] From that point on, the conjecture was reformulated to require two-sided Noetherian rings.

Partial results

Jacobson's conjecture has been verified for particular types of Noetherian rings:

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References

  1. Jacobson, Nathan (1956), Structure of rings, American Mathematical Society, Colloquium Publications, vol. 37, 190 Hope Street, Providence, R. I.: American Mathematical Society, p. 200, MR   0081264 {{citation}}: CS1 maint: location (link). As cited by Brown, K. A.; Lenagan, T. H. (1982), "A note on Jacobson's conjecture for right Noetherian rings", Glasgow Mathematical Journal , 23 (1): 7–8, doi: 10.1017/S0017089500004729 , MR   0641612 .
  2. Herstein 1965.
  3. Jategaonkar 1968.
  4. Cauchon 1974.
  5. Jategaonkar 1974.
  6. Lenagan 1977.
  7. Jategaonkar 1982.

Sources