Tatiana Shulman

  1. Lifting algebraic contractions in C*-algebras.

    Authors: Tatiana Shulman, Terry Loring
    Subjects: Operator Algebras
    Abstract

    Let p be a polynomial in one variable. It is shown that the universal
    C*-algebra of the relation p(x)=0, \|x\| \le C is semiprojective, residually
    finite-dimensional and has trivial extension group.

  2. Noncommutative Semialgebraic Sets in Nilpotent Variables.

    Authors: Terry A. Loring, Tatiana Shulman
    Subjects: Operator Algebras
    Abstract

    We solve the lifting problem in C^*-algebras for many sets of relations that
    include the relations x_j^{N_j} = 0 on each variable. The remaining relations
    must be of the form \| p(x_1,...,x_n) \| \leq C for C a positive constant and p
    a noncommutative *-polynomial that is in some sense homogeneous. For example,
    we prove liftability for the set of relations x^3=0, y^4=0, z^5=0,
    xx^*+yy^*+zz^* \leq 1. Thus we find more noncommutative semialgebraic sets that
    have the topology of noncommutative absolute retracts.

  3. Noncommutative Semialgebraic sets and Associated Lifting Problems.

    Authors: Terry A. Loring, Tatiana Shulman
    Subjects: Operator Algebras
    Abstract

    We solve a class of lifting problems involving approximate polynomial
    relations (``softened polynomial relations''). Various associated C*-algebras
    are therefore projective. The technical lemma we need is a new manifestation of
    Akemann and Pedersen's discovery of the norm adjusting power of quasi-central
    approximate units.

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