Completion of Hankel Partial Contractions of Extremal Type
نویسندگان
چکیده
We find concrete necessary and sufficient conditions for the existence of contractive completions of Hankel partial contractions of size 4×4 in the extremal case. Along the way we introduce a new approach that allows us to solve, algorithmically, the contractive completion problem for 4 × 4 Hankel matrices. As an application, we obtain a concrete example of a partially contractive 4× 4 Hankel matrix which does not admit a contractive completion. b 2000 Mathematics Subject Classification: Primary 47B35, 15A83, 15A60, 15A48; Secondary 47A30, 15-04 c
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