منابع مشابه
C*-algebra generated by projections
The universal C*-algebra generated by n projections has been described. As an immediate corollary one obtains structure theorem for a pair of projections and the solution to an associated index problem. This puts the study of a pair of projections in the proper perspective of noncommutative geometry. keyword: Index problem, crossed product, Fredholm module, pair of projections. MSC 46L87.
متن کاملAlgebra and Geometry under Projections and Applications
Let X be a reduced closed scheme in P and let IX be its saturated defining ideal. As a generalization of property Np due to Green-Larzarsfeld, we say that X satisfies property N2,p if IX has only the simplest linear syzygies up to p-th step. When p = 1, then IX is generated by quadrics. Recently, many interesting geometric results have been proved for projective varieties with property N2,p (se...
متن کاملWeak Projections onto a Braided Hopf Algebra
We show that, under some mild conditions, a bialgebra in an abelian and coabelian braided monoidal category has a weak projection onto a formally smooth (as a coalgebra) sub-bialgebra with antipode; see Theorem 1.12. In the second part of the paper we prove that bialgebras with weak projections are cross product bialgebras; see Theorem 2.12. In the particular case when the bialgebra A is cocomm...
متن کاملProjections from a von Neumann algebra onto a subalgebra
— This paper is mainly devoted to the following question : let M, N be Von Neumann algebras with M C N. If there is a completely bounded projection P : N -^ M, is there automatically a contractive projection P : N -^ M? We give an affirmative answer with the only restriction that M is assumed semi-finite. The main point is the isometric identification of the complex interpolation space (AO, Ai ...
متن کاملSome Classes Containing a Fork Algebra Equivalent Variety Involving Projections
Some varieties that are extensions of relational algebras with two constants that play the role of projections are studied. The classes have as a subvariety the abstract fork algebra (AFA) equivalent variety involving projections. They are obtained by weakening some laws valid in AFA. Some applications of the varieties in the literature and in the specification of abstract data types are exhibi...
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ژورنال
عنوان ژورنال: Mathematical Programming
سال: 1976
ISSN: 0025-5610,1436-4646
DOI: 10.1007/bf01580656