An invariant for pairs of almost commuting unbounded operators
نویسنده
چکیده
For a wide class of pairs of unbounded selfadjoint operators (A,B) with bounded commutator and with operator (1+A2+B2)−1 being compact we construct aK-theoretical integer invariant ω(A,B), which is continuous, is equal to zero for commuting operators and is equal to one for the pair (x,−i d/dx). Such invariants in the case of bounded operators were constructed by T. Loring [1, 3] for matrices realizing ‘almost commutative’ torus and sphere.
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