Changeset f7d745 in git for Singular/LIB/jacobson.lib
- Timestamp:
- May 26, 2011, 1:55:32 PM (13 years ago)
- Branches:
- (u'spielwiese', 'fe61d9c35bf7c61f2b6cbf1b56e25e2f08d536cc')
- Children:
- 38ac8cadfce1628aa28008b1a3d9bbd297dd2983
- Parents:
- 1fe2271e3800804bd9a9bef62db37a53fa11b38e
- File:
-
- 1 edited
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Singular/LIB/jacobson.lib
r1fe227 rf7d745 9 9 OVERVIEW: 10 10 We work over a ring R, that is an Euclidean principal ideal domain. 11 @* If R is commutative, we suppose R to be a polynomial ring in one variable. 12 @* If R is non-commutative, we suppose R to have two variables, say x and d. 13 @* We treat then the basering as the Ore localization of R 14 @* with respect to the mult. closed set S = K[x] without 0. 15 @* Thus, we treat basering as principal ideal ring with d a polynomial 16 @* variable and x an invertible one. 17 @* Note, that in computations no division by x will actually happen. 18 @* 19 @* Given a rectangular matrix M over R, one can compute unimodular (that is 20 @* invertible) square matrices U and V, such that U*M*V=D is a diagonal matrix. 21 @* Depending on the ring, the diagonal entries of D have certain properties. 22 @* 23 @* We call a square matrix D as before 'a weak Jacobson normal form of M'. 24 @* It is known, that over the first rational Weyl algebra K(x)<d>, D can be further 25 @* transformed into a diagonal matrix (1,1,...,1,f,0,..,0), where f is in K(x)<d>. We call 26 @* such a form of D the strong Jacobson normal form. The existence of strong form 27 @* in not guaranteed if one works with algebra, which is not rational Weyl algebra. 11 If R is commutative, we suppose R to be a polynomial ring in one variable. 12 If R is non-commutative, we suppose R to have two variables, say x and d. 13 We treat then the basering as the Ore localization of R 14 with respect to the mult. closed set S = K[x] without 0. 15 Thus, we treat basering as principal ideal ring with d a polynomial 16 variable and x an invertible one. 17 Note, that in computations no division by x will actually happen. 18 19 Given a rectangular matrix M over R, one can compute unimodular (that is 20 invertible) square matrices U and V, such that U*M*V=D is a diagonal matrix. 21 Depending on the ring, the diagonal entries of D have certain properties. 22 23 We call a square matrix D as before 'a weak Jacobson normal form of M'. 24 It is known, that over the first rational Weyl algebra K(x)<d>, D can be further 25 transformed into a diagonal matrix (1,1,...,1,f,0,..,0), where f is in K(x)<d>. 26 We call such a form of D the strong Jacobson normal form. 27 The existence of strong form in not guaranteed if one works with algebra, 28 which is not rational Weyl algebra. 28 29 29 30
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