Seminars: M. V. Zubkov, The join degree spectrum of successor and block relations on computable linear orders

SEMINARS


Computable linear orders and linearly ordered structures October 5, 2019, Kazan, Kremlevskaya str., 35, Kazan Federal University, room 509

The join degree spectrum of successor and block relations on computable linear orders M. V. Zubkov
Abstract: A. Frolov (2012) proved that the degree spectrum of the successor relation of a non-$\eta$-like linear order is closed upwards in enumerable degrees. In the paper of R. Downey, S. Lempp, G. Wu (2012) the similar prove for $\eta$-like linear orders contains a fatal mistake. In this talk we consider the join spectrum of successor and block relations on computable $\eta$-like linear orders. We prove that such join spectrum is closed upwards in enumerable degrees. It is a join work with A. Frolov.