Yiqun Liu

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math.LO2025

Isolated d.c.e. degrees and $Σ_{1}$ induction

Yiqun Liu, Yong Liu, Cheng Peng

A Turing degree is d.c.e. if it contains a set that is the difference of two c.e. sets. A d.c.e. degree $d$ is isolated by a c.e. degree $a < d$ if all c.e…

math.LO2022

On the Nonexistence of a Strong Minimal Pair

Mingzhong Cai, Yiqun Liu, Yong Liu +2

Two nonzero recursively enumerable (r.e.) degrees $a$ and $b$ form a strong minimal pair if $a \land b = 0$ and $\mathbf{b}\vee \mathbf{…

Isolated d.c.e. degrees and Σ1​ induction

On the Nonexistence of a Strong Minimal Pair

Isolated d.c.e. degrees and $Σ_{1}$ induction