Source: J. Symbolic Logic Volume 74, Issue 4
(2009), 1310-1324.
The Rainbow Ramsey Theorem is essentially an “anti-Ramsey" theorem
which states that certain types of colorings must be injective on a
large subset (rather than constant on a large subset). Surprisingly,
this version follows easily from Ramsey's Theorem, even in the weak
system RCA0 of reverse mathematics. We answer the question of the
converse implication for pairs, showing that the Rainbow Ramsey
Theorem for pairs is in fact strictly weaker than Ramsey's Theorem for pairs
over RCA0. The separation involves techniques from the theory of
randomness by showing that every 2-random bounds an ω-model
of the Rainbow Ramsey Theorem for pairs. These results also provide
as a corollary a new proof of Martin's theorem that the hyperimmune
degrees have measure one.
References
Uri Abraham, James Cummings, and Clifford Smyth, Some results in polychromatic Ramsey theory, Journal of Symbolic Logic, vol. 72 (2007), no. 3, pp. 865--896.
Brian Alspach, Martin Gerson, Geňa Hahn, and Pavol Hell, On sub-Ramsey numbers, Ars Combinatoria, vol. 22 (1986), pp. 199--206.
Mathematical Reviews (MathSciNet):
MR867747
Peter A. Cholak, Carl G. Jockusch, and Theodore A. Slaman, On the strength of Ramsey's theorem for pairs, Journal of Symbolic Logic, vol. 66 (2001), no. 1, pp. 1--55.
S. Barry Cooper, Computability theory, Chapman & Hall/CRC, Boca Raton, FL, 2004.
Rod Downey and Denis R. Hirschfeldt, Algorithmic randomness and complexity, Springer-Verlag,to appear.
Rod Downey, Denis R. Hirschfeldt, André Nies, and Sebastiaan A. Terwijn, Calibrating randomness, Bulletin of Symbolic Logic, vol. 12 (2006), no. 3, pp. 411--491.
Pavol Hell and Juan José Montellano-Ballesteros, Polychromatic cliques, Discrete Mathematics, vol. 285 (2004), no. 1-3, pp. 319--322.
Denis R. Hirschfeldt and Richard A. Shore, Combinatorial principles weaker than Ramsey's theorem for pairs, Journal of Symbolic Logic, vol. 72 (2007), no. 1, pp. 171--206.
Carl G. Jockusch, Jr., Ramsey's theorem and recursion theory, Journal of Symbolic Logic, vol. 37 (1972), pp. 268--280.
Mathematical Reviews (MathSciNet):
MR376319
Carl G. Jockusch, Jr. and Robert I. Soare, $\Pi \sp0\sb1$ classes and degrees of theories, Transactions of the American Mathematical Society, vol. 173 (1972), pp. 33--56.
Mathematical Reviews (MathSciNet):
MR316227
Antonín Kučera, Measure, $\Pi\sp 0\sb 1$-classes and complete extensions of $\rm PA$, Recursion theory week (Oberwolfach, 1984), Lecture Notes in Math., vol. 1141, Springer, Berlin, 1985, pp. 245--259.
Mathematical Reviews (MathSciNet):
MR820784
Joseph R. Mileti, Partition theorems and computability theory, Ph.D. thesis, University of Illinois at Urbana-Champaign, 2004.
--------, The canonical Ramsey theorem and computability theory, Transactions of the American Mathematical Society, vol. 360 (2008), no. 3, pp. 1309--1340 (electronic).
Andre Nies, Computability and randomness, Oxford University Press, New York, 2009.
David Seetapun and Theodore A. Slaman, On the strength of Ramsey's theorem, Notre Dame Journal of Formal Logic, vol. 36 (1995), no. 4, pp. 570--582, Special Issue: Models of arithmetic.
Stephen G. Simpson, Subsystems of second order arithmetic, Perspectives in Mathematical Logic, Springer-Verlag, Berlin, 1999.
Robert I. Soare, Recursively enumerable sets and degrees, Perspectives in Mathematical Logic, Springer-Verlag, Berlin, 1987, A study of computable functions and computably generated sets.
Mathematical Reviews (MathSciNet):
MR882921
Stevo Todorčević, Forcing positive partition relations, Transactions of the American Mathematical Society, vol. 280 (1983), no. 2, pp. 703--720.
Mathematical Reviews (MathSciNet):
MR716846
Michiel van Lambalgen, Random sequences, Ph.D. thesis, University of Amsterdam, 1987.