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Andrew Lewis

Graduate Theological Union
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  • Graduate Theological Union
    Department of Philosophy
    Doctoral student
  • All publications (19)
  •  489
    The ibT degrees of computably enumerable sets are not dense
    with George Barmpalias
    Annals of Pure and Applied Logic 141 (1): 51-60. 2006.
    We show that the identity bounded Turing degrees of computably enumerable sets are not dense
    Logic and Philosophy of LogicLogic and Philosophy of Logic, MiscellaneousModel Theory
  •  115
    A C.E. Real That Cannot Be SW-Computed by Any Ω Number
    with George Barmpalias
    Notre Dame Journal of Formal Logic 47 (2): 197-209. 2006.
    The strong weak truth table (sw) reducibility was suggested by Downey, Hirschfeldt, and LaForte as a measure of relative randomness, alternative to the Solovay reducibility. It also occurs naturally in proofs in classical computability theory as well as in the recent work of Soare, Nabutovsky, and Weinberger on applications of computability to differential geometry. We study the sw-degrees of c.e. reals and construct a c.e. real which has no random c.e. real (i.e., Ω number) sw-above it
    Set Theory
  •  83
    The importance of Π1 0 classes in effective randomness
    with George Barmpalias and Keng Meng Ng
    Journal of Symbolic Logic 75 (1): 387-400. 2010.
    We prove a number of results in effective randomness, using methods in which Π⁰₁ classes play an essential role. The results proved include the fact that every PA Turing degree is the join of two random Turing degrees, and the existence of a minimal pair of LR degrees below the LR degree of the halting problem.
    Logic and Philosophy of LogicLogic and Philosophy of Logic, MiscellaneousSet Theory
  •  79
    A call for an expanded synthesis of developmental and evolutionary paradigms
    Behavioral and Brain Sciences 35 (5): 368-369. 2012.
    Charney's target article continues a critique of genetic blueprint models of development that suggests reconsideration of concepts of adaptation, inheritance, and environment, which can be well illustrated in current research on infant attachment. The concepts of development and adaptation are so heavily based on the model of genetics and inheritance forged in the modern synthesis that they will require reconsideration to accommodate epigenetic inheritance
    Philosophy of Cognitive ScienceEvolutionary Developmental BiologyNature and Nurture
  •  75
    The Hypersimple-Free C.E. WTT Degrees Are Dense in the C.E. WTT Degrees
    with George Barmpalias
    Notre Dame Journal of Formal Logic 47 (3): 361-370. 2006.
    We show that in the c.e. weak truth table degrees if b < c then there is an a which contains no hypersimple set and b < a < c. We also show that for every w < c in the c.e. wtt degrees such that w is hypersimple, there is a hypersimple a such that w < a < c. On the other hand, we know that there are intervals which contain no hypersimple set
    Set Theory
  •  67
    Empty intervals in the enumeration degrees
    with Thomas F. Kent and Andrea Sorbi
    Annals of Pure and Applied Logic 163 (5): 567-574. 2012.
    Science, Logic, and MathematicsLogic and Philosophy of Logic, Miscellaneous
  •  56
    Topological aspects of the Medvedev lattice
    with Richard A. Shore and Andrea Sorbi
    Archive for Mathematical Logic 50 (3-4): 319-340. 2011.
    We study the Medvedev degrees of mass problems with distinguished topological properties, such as denseness, closedness, or discreteness. We investigate the sublattices generated by these degrees; the prime ideal generated by the dense degrees and its complement, a prime filter; the filter generated by the nonzero closed degrees and the filter generated by the nonzero discrete degrees. We give a complete picture of the relationships of inclusion holding between these sublattices, these filters, …Read more
    We study the Medvedev degrees of mass problems with distinguished topological properties, such as denseness, closedness, or discreteness. We investigate the sublattices generated by these degrees; the prime ideal generated by the dense degrees and its complement, a prime filter; the filter generated by the nonzero closed degrees and the filter generated by the nonzero discrete degrees. We give a complete picture of the relationships of inclusion holding between these sublattices, these filters, and this ideal. We show that the sublattice of the closed Medvedev degrees is not a Brouwer algebra. We investigate the dense degrees of mass problems that are closed under Turing equivalence, and we prove that the dense degrees form an automorphism base for the Medvedev lattice. The results hold for both the Medvedev lattice on the Baire space and the Medvedev lattice on the Cantor space.
    Logic and Philosophy of Logic, Miscellaneous
  •  50
    Disorganized attachment and reproductive strategies
    with Gregory Tooley
    Behavioral and Brain Sciences 32 (1): 35-36. 2009.
    Del Giudice provides an extension of the life history theory of attachment that incorporates emerging data suggestive of sex differences in avoidant male and preoccupied female attachment patterns emerging in middle childhood. This commentary considers the place of disorganized attachment within this theory and why male children may be more prone to disorganized attachment by drawing on Trivers's parental investment theory
    Consciousness and Psychology
  •  44
    Π 1 0 classes, L R degrees and Turing degrees
    with George Barmpalias and Frank Stephan
    Annals of Pure and Applied Logic 156 (1): 21-38. 2008.
    We say that A≤LRB if every B-random set is A-random with respect to Martin–Löf randomness. We study this relation and its interactions with Turing reducibility, classes, hyperimmunity and other recursion theoretic notions.
    Logic and Philosophy of LogicLogic and Philosophy of Logic, Miscellaneous
  •  41
    Randomness and the linear degrees of computability
    with George Barmpalias
    Annals of Pure and Applied Logic 145 (3): 252-257. 2007.
    We show that there exists a real α such that, for all reals β, if α is linear reducible to β then β≤Tα. In fact, every random real satisfies this quasi-maximality property. As a corollary we may conclude that there exists no ℓ-complete Δ2 real. Upon realizing that quasi-maximality does not characterize the random reals–there exist reals which are not random but which are of quasi-maximal ℓ-degree–it is then natural to ask whether maximality could provide such a characterization. Such hopes, howe…Read more
    We show that there exists a real α such that, for all reals β, if α is linear reducible to β then β≤Tα. In fact, every random real satisfies this quasi-maximality property. As a corollary we may conclude that there exists no ℓ-complete Δ2 real. Upon realizing that quasi-maximality does not characterize the random reals–there exist reals which are not random but which are of quasi-maximal ℓ-degree–it is then natural to ask whether maximality could provide such a characterization. Such hopes, however, are in vain since no real is of maximal ℓ-degree
    Science, Logic, and MathematicsAreas of MathematicsComputability
  •  40
    Randomness, Lowness and Degrees
    with George Barmpalias and Mariya Soskova
    Journal of Symbolic Logic 73 (2). 2008.
    We say that A ≤LR B if every B-random number is A-random. Intuitively this means that if oracle A can identify some patterns on some real γ. In other words. B is at least as good as A for this purpose. We study the structure of the LR degrees globally and locally (i.e., restricted to the computably enumberable degrees) and their relationship with the Turing degrees. Among other results we show that whenever α in not GL₂ the LR degree of α bounds $2^{\aleph _{0}}$ degrees (so that, in particular,…Read more
    We say that A ≤LR B if every B-random number is A-random. Intuitively this means that if oracle A can identify some patterns on some real γ. In other words. B is at least as good as A for this purpose. We study the structure of the LR degrees globally and locally (i.e., restricted to the computably enumberable degrees) and their relationship with the Turing degrees. Among other results we show that whenever α in not GL₂ the LR degree of α bounds $2^{\aleph _{0}}$ degrees (so that, in particular, there exist LR degrees with uncountably many predecessors) and we give sample results which demonstrate how various techniques from the theory of the c.e. degrees can be used to prove results about the c.e. LR degrees
    Mathematical Logic
  •  33
    Isaac Newton Institute, Cambridge, UK July 2–6, 2012
    with George Barmpalias, Vasco Brattka, Adam Day, Rod Downey, John Hitchcock, Michal Koucký, Jack Lutz, André Nies, and Alexander Shen
    Bulletin of Symbolic Logic 19 (1). 2013.
    Science, Logic, and Mathematics
  •  31
    Diagonally non-computable functions and bi-immunity
    with Carl G. Jockusch
    Journal of Symbolic Logic 78 (3): 977-988. 2013.
    Logic and Philosophy of LogicLogic and Philosophy of Logic, Miscellaneous
  •  29
    Trajectories of Early Childhood Developmental Skills and Early Adolescent Psychotic Experiences: Findings from the ALSPAC UK Birth Cohort
    with Mohajer A. Hameed, Raghu Lingam, Stanley Zammit, Giovanni Salvi, and Sarah Sullivan
    Frontiers in Psychology 8. 2018.
    Philosophy of Cognitive Science
  •  29
    GM vs Climate Change
    Philosophy Now 65 14-15. 2008.
    Climate Change
  •  29
    Nijmegen, The Netherlands July 27–August 2, 2006
    with Rodney Downey, Ieke Moerdijk, Boban Velickovic, Samson Abramsky, Marat Arslanov, Harvey Friedman, Martin Goldstern, Ehud Hrushovski, and Jochen Koenigsmann
    Bulletin of Symbolic Logic 13 (2). 2007.
    Science, Logic, and Mathematics
  •  15
    2008 Annual Meeting of the Association for Symbolic Logic-University of California, Irvine-Irvine, California-March 27-30, 2008-Abstracts (review)
    with Sam Buss, Stephen Cook, Jos Ferreirs, David Marker, Theodore Slaman, and Jamie Tappenden
    Bulletin of Symbolic Logic 14 (3): 418-437. 2008.
    Logic and Philosophy of LogicLogic and Philosophy of Logic, Misc
  •  2
    The Role of Supervision in the Training of a Psychoanalyst
    Analysis (Australian Centre for Psychoanalysis) 13 85. 2007.
    Ethics
  • The importance of $\Pi _1^0$ classes in effective randomness. The Journal of Symbolic Logic, vol. 75
    with George Barmpalias, Keng Meng Ng, and Frank Stephan
    Bulletin of Symbolic Logic 18 (3): 409-412. 2012.
    Logic and Philosophy of LogicLogic and Philosophy of Logic, Miscellaneous
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