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  1. George Barmpalias & Angsheng Li (2013). Kolmogorov Complexity and Computably Enumerable Sets. Annals of Pure and Applied Logic 164 (12):1187-1200.
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  2. Paul Brodhead, Angsheng Li & Weilin Li (2008). Continuity of Capping In. Annals of Pure and Applied Logic 155 (1):1-15.
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  3. S. Barry Cooper & Angsheng Li (2008). On Lachlan's Major Sub-Degree Problem. Archive for Mathematical Logic 47 (4):341-434.
    The Major Sub-degree Problem of A. H. Lachlan (first posed in 1967) has become a long-standing open question concerning the structure of the computably enumerable (c.e.) degrees. Its solution has important implications for Turing definability and for the ongoing programme of fully characterising the theory of the c.e. Turing degrees. A c.e. degree a is a major subdegree of a c.e. degree b > a if for any c.e. degree x, ${{\bf 0' = b \lor x}}$ if and only if (...)
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  4. Chi Tat Chong, Angsheng Li & Yue Yang (2006). The Existence of High Nonbounding Degrees in the Difference Hierarchy. Annals of Pure and Applied Logic 138 (1):31-51.
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  5. Angsheng Li, Guohua Wu & Yue Yang (2006). Bounding Computably Enumerable Degrees in the Ershov Hierarchy. Annals of Pure and Applied Logic 141 (1):79-88.
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  6. S. Barry Cooper, Angsheng Li, Andrea Sorbi & Yue Yang (2005). Bounding and Nonbounding Minimal Pairs in the Enumeration Degrees. Journal of Symbolic Logic 70 (3):741 - 766.
    We show that every nonzero $\Delta _{2}^{0}$ e-degree bounds a minimal pair. On the other hand, there exist $\Sigma _{2}^{0}$ e-degrees which bound no minimal pair.
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  7. Rod Downey, Angsheng Li & Guohua Wu (2004). Complementing Cappable Degrees in the Difference Hierarchy. Annals of Pure and Applied Logic 125 (1-3):101-118.
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  8. Dengfeng Li & Angsheng Li (2003). A Minimal Pair Joining to a Plus Cupping Turing Degree. Mathematical Logic Quarterly 49 (6):553-566.
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  9. Yong Wang & Angsheng Li (2003). A Hierarchy for the Plus Cupping Turing Degrees. Journal of Symbolic Logic 68 (3):972-988.
    We say that a computably enumerable (c. e.) degree a is plus-cupping, if for every c.e. degree x with $0 < x \leq a$ , there is a c. e. degree $y \not= 0'$ such that $x \vee y = 0/\'$ . We say that a is n-plus-cupping. if for every c. e. degree x, if $0 < x \leq a$ , then there is a $low_n$ c. e. degree 1 such that $x \vee l = 0'$ . Let PC (...)
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  10. S. Barry Cooper & Angsheng Li (2002). Splitting and Nonsplitting, II: A $Low_2$ C.E. Degree Above Which 0' is Not Splittable. Journal of Symbolic Logic 67 (4):1391-1430.
    It is shown that there exists a low2 Harrington non-splitting base-that is, a low2 computably enumerable (c.e.) degree a such that for any c.e. degrees x, y, if $0' = x \vee y$ , then either $0' = x \vee a$ or $0' = y \vee a$ . Contrary to prior expectations, the standard Harrington non-splitting construction is incompatible with the $low_{2}-ness$ requirements to be satisfied, and the proof given involves new techniques with potentially wider application.
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  11. S. Barry Cooper, Angsheng Li & Xiaoding Yi (2002). On the Distribution of Lachlan Nonsplitting Bases. Archive for Mathematical Logic 41 (5):455-482.
    We say that a computably enumerable (c.e.) degree b is a Lachlan nonsplitting base (LNB), if there is a computably enumerable degree a such that a > b, and for any c.e. degrees w,v ≤ a, if a ≤ w or; v or; b then either a ≤ w or; b or a ≤ v or; b. In this paper we investigate the relationship between bounding and nonbounding of Lachlan nonsplitting bases and the high /low hierarchy. We prove that there (...)
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  12. Angsheng Li (2000). Bounding Cappable Degrees. Archive for Mathematical Logic 39 (5):311-352.
    It will be shown that there exist computably enumerable degrees a and b such that a $>$ b, and for any computably enumerable degree u, if u $\leq$ a and u is cappable, then u $<$ b.
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  13. Angsheng Li (2000). On a Conjecture of Lempp. Archive for Mathematical Logic 39 (4):281-309.
    In this paper, we first prove that there exist computably enumerable (c.e.) degrees a and b such that ${\bf a\not\leq b}$ , and for any c.e. degree u, if ${\bf u\leq a}$ and u is cappable, then ${\bf u\leq b}$ , so refuting a conjecture of Lempp (in Slaman [1996]); secondly, we prove that: (A. Li and D. Wang) there is no uniform construction to build nonzero cappable degree below a nonzero c.e. degree, that is, there is no computable function (...)
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  14. Angsheng Li & Dongping Yang (1998). Bounding Minimal Degrees by Computably Enumerable Degrees. Journal of Symbolic Logic 63 (4):1319-1347.
    In this paper, we prove that there exist computably enumerable degrees a and b such that $\mathbf{a} > \mathbf{b}$ and for any degree x, if x ≤ a and x is a minimal degree, then $\mathbf{x}.
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