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3. Rodney G. Downey, Carl G. Jockusch, Jr., and Paul E. Schupp, Asymptotic density and computably enumerable sets, Journal of Mathematical Logic, to appear.

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9. R. Soare, Cohesive sets and recursively enumerable Dedekind cuts, Pacific J. Math. 31 (1969), 215-231. School of Mathematics, Statistics, and Operations Research, Victoria University of Wellington, New Zealand E-mail address: Rod.Downey@msor.vuw.ac.nz Department of Mathematics, University of Illinois at Urbana-Champaign, 1409 W. [OpenAIRE]

Green St., Urbana, Illinois 61801 USA E-mail address: jockusch@math.uiuc.edu Department of Mathematics, University of Illinois at Urbana-Champaign, 1409 W.

Green St., Urbana, Illinois 61801 USA E-mail address: schupp@math.uiuc.edu