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A computably enumerable (c.e., for short) degree a is called plus cupping, if every c.e. degree x with 0<x⩽a is cuppable. Let PC be the set of all plus cupping degrees. In the present paper, we show that PC is not closed under the join operation v by constructing two plus cupping degrees which join to a high degree. So by the Harrington’s noncupping theorem, PC is not an ideal of ε.
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