Joint hyponormality of rational Toeplitz pairs
نویسندگان
چکیده
We characterize hyponormal “rational” Toeplitz pairs which are pairs of Toeplitz operators whose symbols are rational functions in L∞. The main result of this article is as follows. If T = (Tφ, Tψ) is a hyponormal rational Toeplitz pair then φ− βψ ∈ H for some constant β; in other words, their co-analytic parts necessarily coincide up to a constant multiple. As a corollary we get a complete characterization of hyponormal rational Toeplitz pairs. Mathematics Subject Classification (2000). Primary 47B20, 47B35, 47A13.
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