Department of Mathematics, Central South University, South Campus, South Dormitory No. 6 Room 619, Changsha, 410083, China, E-mail: email@example.com
We prove that by showing that for any set C not of PA-degree and any set A, there exists an infinite subset G of A or such that G ⊕ C is also not of PA-degree.
(Received October 26 2010)
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