Our definition effectively reduces to the classical notion in the atomic abelian case, has both concrete and intrinsic characterizations, and admits a wide variety of tractable examples. General facts concerning measurable operators may be found in, see also 49, chapter ix and the forthcoming book. The coverage provided, albeit not always uptodate, acquaints the reader with both basic and more advanced tools. But is is quite hard, in general, to get much control over the operators added when taking the. This is best seen in the torsion free abelian case, where cgremembers gcompletely 1supported by a clay research fellowship. Then the space of all bounded operators bh is a c algebra when endowed with the operator norm kxk sup. Let abe a unital banach algebra and suppose x2asuch that. Cz with the algebra of laurent polynomials c z1 considered as functions on s1. We have previously met examples of factors, namely the factors bh where h is a finite or infinite dimensional hilbert. In 1943, gelfand and naimark introduced the notion of a c algebra, namely a banach algebra with an involution satisfying kak kakand kaak kak2. We prove the following theorem which answers a question of ge ge that whether the free group factors are solid.
For convenience of the reader, some of the basic definitions are recalled. This will be made precise later on, but for now take it as an indication that the intuition will shift from topological spaces to measure spaces. By continuing to use our website, you are agreeing to our use of cookies. Proof of the theorem we recall the following principle ch. Operator algebras, linear functionals on an operator algebra, kaplanskys density theorem, positive continuous linear functionals, disjoint representations of a c algebra, the tomitatakesaki modular operator, the canonical commutation. When passing from cgto lg, the memory of gtends to fade away. This is not particularly illuminating but can be useful at math parties. The topology induced by this convergence is called the strong operator topology or sot. The factors are classi ed by means of a relative dimension function into type in, ii1, ii1, iii factors. Volume 228, issue 5, 1 december 2011, pages 26472671. They showed that if such an algebra ais commutative, then it is. We describe these consequences of our postulate in sec.
Its a book i would definitely recommend to anyone interested in the topic. Indeed, if g is abelian torsion free, then the group of connected. Jones 1 november, 2015 1supportedinpartbynsfgrantdms9322675,themarsdenfunduoa520, andtheswissnationalsciencefoundation. Inherent defects at the most basic level cause them to be both fat and weak. By interpreting the modular ow as the physical time ow, this result assumes a deep physical signi. Conventional programming languages are growing ever more enormous, but not stronger. Jones 1 october 1, 2009 1supportedinpartbynsfgrantdms9322675,themarsdenfunduoa520, andtheswissnationalsciencefoundation. Basic properties of the relative entropy are proved for this generalization. Chapter 1 spectral theory if ais a complex unital algebra then we denote by ga the set of elements which have a two sided inverse. Classifying lg in terms of g emerged from the beginning as a natural yet quite challenging problem as these algebras tend to have very limited memory of the underlying group. We prove the following theorem which answers a question of ge that whether the free group factors are solid.
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