Abstract
In August 1987 I attended an inspiring talk by Paul Halmos at Chapman College in Orange, California. It was entitled “Some Problems You Can Solve, and Some You Cannot.” This problem was an example of a problem “you cannot solve.”
Much but not all of this text is contained in the author’s monograph [Soi].
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Notes
- 1.
[Bru6].
- 2.
This seems to be my first mention of what has become an 18-year long project!
- 3.
First publication could be attributed to De Morgan, who mentioned the problem in his 1860 book review in Athenaeum [DeM4], albeit anonymously.
- 4.
Thanks to Prof. Fred Hoffman, the tireless organizer of this annual conference, I have a videotape of Paul Erdős’s memorable talk.
- 5.
My translation from the Russian.
- 6.
Ibid.
- 7.
The Young Men’s Christian Association (YMCA) is one of the oldest and largest not-for-profit community service organizations in the world.
- 8.
Robert Maynard Hutchins (1899–1977) was President (1929–1945) and Chancellor (1945–1951) of the University of Chicago.
- 9.
Graham cites Paul O’Donnell’s Theorem 48.4 (see it later in this book) as “perhaps, the evidence that χ is at least 5.”
- 10.
If the chromatic number of the plane is 7, then for G(x 1,…,xn)=7 such an n must be greater than 6197 [Pri].
- 11.
The authors of the fine problem book [BMP] incorrectly credit Hadwiger as “first” to study this problem (p. 235). Hadwiger, quite typically for him, limited his study to partitions into closed sets.
- 12.
Students in such high schools hold regular jobs during the day, and attend classes at night.
- 13.
The axiom of choice is assumed in this result.
- 14.
Or so we all thought until recently. Because of that, I chose to leave this section as it was written in the early 1990s. BUT: see Section X of this survey for the latest developments.
- 15.
The symbol G(x 1,…,x n ) denotes the graph on the listed inside parentheses n vertices, with two vertices adjacent if and only if they are unit distance apart.
- 16.
Symbol [a,b], a < b, as usual, stands for the line segment, including its endpoints a and b.
- 17.
The important problem book [BMP] mistakenly cites only one of this series of three papers. It also incorrectly states that the authors proved only the lower bound 5, whereas they raised the lower bound to 6.
- 18.
Curiously, Paul wrote an improbable date on the letter: “1977 VII 25”.
- 19.
The De Bruijn–Erdős theorem assumes the axiom of choice.
- 20.
Quoted from [Pet], p. 494.
- 21.
It is the first task, but we did not think of it then, and so this definition appears for the first time in [Soi].
- 22.
Quoted from [Pet], p. 494.
- 23.
A cardinal κ is called inaccessible if κ>ℵ 0, κ is regular, and κ is strong limit. An infinite cardinal ℵ α is regular, if cfωα=ωα. A cardinal κ is a strong limit cardinal if for every cardinal λ, λ<κ implies2λ<κ.
- 24.
Assuming the existence of an inaccessible cardinal.
- 25.
Due to the use of the Solovay’s theorem, we assume the existence of an inaccessible cardinal.
References
Bruijn, N. G. de, and Erdős, P., A colour problem for infinite graphs and a problem in the theory of relations, Indagationes Math. 13 (1951), 369–373.
Benda, M., and Perles, M., Colorings of metric spaces, Geombinatorics IX(3), (2000), 113–126.
Brass, P., Moser, W., and Pach, J., Research Problems in Discrete Geometry, Springer, New York, 2006.
Brown, N., Dunfield, N., and Perry, G., Colorings of the plane I, Geombinatorics III(2), (1993), 24–31.
Brown, N., Dunfield, N., and Perry, G., Colorings of the plane II, Geombinatorics III(3), (1993), 64–74.
Brown, N., Dunfield, N., and Perry, G., Colorings of the plane III, Geombinatorics III(4), (1993), 110–114.
Cantwell, K., All regular polytopes are Ramsey, J. Combin. Theory Ser A 114 (2007) 555–562.
Chilakamarri, K. B., Unit-distance graphs in rational n-spaces, Discrete Math. 69 (1988), 213–218.
Chilakamarri, K. B., On the chromatic number of rational five-space, Aequationes Math. 39 (1990), 146–148.
Chilakamarri, K. B., The unit-distance graph problem: A brief survey and some new results, Bull. ICA 8 (1993), 39–60.
Chow, T., Distances forbidden by two-colorings of Q 3 and A n (manuscript).
Cibulka, J., On the chromatic number of real and rational spaces, Geombinatorics XVIII(2), (2008), 53–65.
Conway, J. H., and Sloane, N. J. A. Sphere Packings, Lattices and Groups, 3rd ed., with contrib. by E. Bannai, R. E. Borcherds, J. Leech, S. P. Norton, A. M. Odlyzko, R. A. Parker, L. Queen, and B. B. Venkov, Springer, New York, 1999.
Coulson, D., A 15-colouring of 3-space omitting distance one, Discrete Math. 256 (1–2), (2002), 83–90.
Coulson, D., Tilings and colourings of 3-space, Geombinatorics XII (3), (2003), 102–116.
Croft, H. T., Incidence incidents, Eureka (Cambridge) 30 (1967), 22–26.
Croft, H. T., Falconer, K. J., and Guy, R. K., Unsolved Problems in Geometry, Springer, New York, 1991.
De Morgan, A., Review of the philosophy of discovery…, The Athenaeum 1694, London, 1860, 501–503.
Erdős, P., Graph theory and probability II, Can. J. Math. 13 (1961), 346–352.
Erdős, P., Some unsolved problems, Magyar tudomanyos academia mathematikai kutato intezetenek közlemenyel 6 ser. A(1–2), (1961), 221–254.
Erdős, P., Nekotorye Nereshennye Problemy (Some unsolved problems), Matematika 7(4), (1963), 109–143. (A Russian translation of [E61.22].)
Erdős, P., On some problems of elementary and combinatorial geometry, Annali Matematica Pura Applicata 103(4), (1975), 99–108.
Erdős, P., Problem (p. 681); P. Erdős, Chairman, Unsolved problems, in Proceedings of the Fifth British Combinatorial Conference 1975, University of Aberdeen, July 14–18, 1975, C. St. J. A. Nash-Williams and J. Sheehan, eds., Congressus Numerantium XV, Winnipeg, Utilitas Mathematica, 1976.
Erdős, P., Problem 28 in “Exercises, problems and conjectures,” in Bollobás, B., Extremal Graph Theory, London Mathematical Society Monographs, Academic Press, 1978, p. 285.
Erdős, P., Combinatorial problems in geometry and number theory, Relations between combinatorics and other parts of mathematics, Proc. of the Sympos. Pure Math., Ohio State Univ., Columbus, OH, (1978); Proc. of the Sympos. Pure Math., XXXIV, Amer. Math. Soc., Providence, RI, (1979), 149–162.
Erdős, P., Some combinatorial problems in geometry, Geom. & Diff. Geom. Proc., Haifa, Israel, (1979); Lecture Notes in Math., 792, Springer (1980), 46–53.
Erdős, P., Some combinational problems in geometry, Geometry and Differential Geometry (Proc. Conf., Univ. Haifa, Haifa, 1979), Lecture Notes in Math., 792, pp. 46–53, Springer, Berlin, 1980.
Erdős, P., Some applications of graph theory and combinatorial methods to number theory and geometry, Algebraic Methods in Graph Theory (Colloq. held in Szeged, Hungary 1978), Vol. I, Coll. Math Soc. J. Bolyai 25 (1981), 137–148.
Erdős, P., Some new problems and results in graph theory and other branches of combinatorial mathematics, Combinatorics and Graph Theory, Proc. Symp. Calcutta 1980, Lecture Notes Math., 885, Springer, 1981, 9–17.
Erdős, P., Problems and results in combinatorial geometry, Discrete Geometry and Convexity, Annals of the New York Academy of Sciences, 440, The New York Academy of Sciences, New York, 1985, 1–11.
Erdős, P., Letter to A. Soifer of July 16, 1991.
Erdős, P., Letter to A. Soifer of August 10, 1991.
Erdős, P., Letter to A. Soifer, received on October 2, 1991 (marked “1977 VII 25”).
Erdős, P., On some unsolved problems in elementary geometry (Hungarian), Mat. Lapok (N.S.) 2(2), (1992), 1–10.
Erdős, P., Video recording of the talk “Some of my favorite problems II”, University of Colorado at Colorado Springs, January 10, 1992.
Erdős, P., Video recording of the talk “Twenty five years of questions and answers,” 25th South-Eastern International Conference On Combinatorics, Graph Theory and Computing, Florida Atlantic University, Boca Raton, March 10, 1994.
Erdős, P., Harary, F., and Tutte, W. T., On the dimension of a graph, Mathematica 12(1965), 118–125.
Erdős, P., and Simonovits, M., On the chromatic number of geometric graphs, Ars Comb. 9 (1980), 229–246.
Falconer, K. J., The realization of distances in measurable subsets covering R n, J.Combin. Theory (A) 31 (1981), 187–189.
Fischer, K. G., Additive k-colorable extensions of the rational plane, Discrete Math. 82 (1990), 181–195.
Fischer, K. G., The connected components of the graph \(Q(Q{(\sqrt{{N}_{1}},\ldots,\sqrt{{N}_{d}})}^{2}\), Congressus Numerantium 72 (1990), 213–221.
Frankl, P., and Wilson, R. M., Intersection theorems with geometric consequences, Combinatorica 1 (1981), 357–368.
Garsia, A., E-mail to A. Soifer, February 28, 1995.
Graham, R. L., Talk at the Mathematical Sciences Research Institute, Berkeley, August 2003.
Graham, R. L., Some of my favorite problems in Ramsey theory, Proceedings of the ‘Integers Conference 2005’ in Celebration of the 70th Birthday of Ronald Graham, Carrolton, Georgia, USA, October 27–30, 2005, B. Landman et al., ed., Walter de Gruyter, Berlin, 2007, 229–236.
Graham, R. L., Old and new problems and results in Ramsey theory, Horizon of Combinatorics (Conference and EMS Summer School), Budapest and Lake Balaton, Hungary, 10–22 July 2006, to appear.
Graham, R. L., and Tressler, E., Open problems in Euclidean Ramsey theory, in this volume.
Goodman, J. E., and O’Rourke, J., Handbook of Discrete and Computational Geometry, CRC Press, Boca Raton, FL, 1997.
Hadwiger, H., Uberdeckung des euklidischen Raum durch kongruente Mengen, Portugaliae Math. 4 (1945), 238–242.
Hadwiger, H., Ungelöste Probleme, Nr. 11, Elemente der Mathematik 16 (1961), 103–104.
Hadwiger, H., and Debrunner, H., Ausgewählte einzelprobleme der kombinatorishen geometrie in der ebene, L’Enseignement Mathematique 1 (1955), 56–89.
Hadwiger, H., and Debrunner, H., Kombinatorischen Geometrie in der Ebene, L’Enseignement Mathematique, Geneva, 1959.
Hadwiger, H., and Debrunner, H., Combinatorial Geometry of the Plane ed. I. M. Yaglom, Nauka, Moscow, 1965 (extended by the editor Russian Translation version of [HD2]).
Hadwiger, H., Debrunner, H., and Klee, V., Combinatorial Geometry in the Plane, Holt, Rinehart and Winston, NY, 1964.
Hochberg, R., and O’Donnell, P., Some 4-chromatic unit-distance graphs without small cycles, Geombinatorics V(4), (1996), 137–14.
Hoffman, I., and Soifer, A., Almost chromatic number of the plane, Geombinatorics III(2), (1993), 38–40.
Hoffman, I., and Soifer, A., Another six-coloring of the plane, Discrete Math. 150 (1996), 427–429.
Isbell, J., Letter to A. Soifer of August 26, 1991.
Isbell, J., Letter to A. Soifer of September 3, 1991.
Johnson Jr., P. D., Coloring Abelian groups, Discrete Math. 40 (1982), 219–223.
Johnson Jr., P. D., Simple product colorings, Discrete Math. 48 (1984), 83–85.
Johnson Jr., P. D., Two-coloring of real quadratic extensions of Q 2 that forbid many distances, Congressus Numerantium 60 (1987), 51–58.
Johnson Jr., P. D., Two-colorings of a dense subgroup of Q n that forbid many distances, Discrete Math. 79 (1989/1990), 191–195.
Johnson Jr., P. D., Product colorings, Geombinatorics I(3), (1991), 11–12.
Johnson Jr., P. D., Maximal sets of translations forbidable by two-colorings of Abelian groups, Congressus Numerantium 91 (1992), 153–158.
Johnson Jr., P. D., About two definitions of the fractional chromatic number, Geombinatorics V(3), (1996), 11–12.
Johnson Jr., P. D., Introduction to “colorings of metric spaces” by Benda and Perles, Geombinatorics IX(3), (2000), 110–112.
Johnson Jr., P. D., Coloring the rational points to forbid the distance one – A tentative history and compendium, Geombinatorics XVI(1), (2006), 209–218.
Johnson Jr., P. D., Euclidean distance graphs on the rational points, appears in this volume.
Jungreis, D. S., Reid, M., and Witte, D., Distances forbidden by some 2-coloring of Q 2, Discrete Math. 82 (1990), 53–56.
Klee, V., and Wagon, S., Old and New Unsolved Problems in Plane Geometry and Number Theory, Mathematical Association of America, second edition (with addendum), 1991.
Larman, D. G., and Rogers, C. A., The realization of distances within sets in Euclidean space, Mathematika 19 (1972), 1–24.
Lovász, L., and Vesztergombi, K., Geometric representations of graphs, in Paul Erdös and his Mathematics II, Halás, G. et al. (ed.), Springer, 2002, 471–498.
Mann, M., A new bound for the chromatic number of the rational five-space, Geombinatorics XI(2), (2001), 49–53.
Mann, M., Hunting unit-distance graphs in rational n-spaces, Geombinatorics XIII(2), (2003), 86–97.
Moser, L., and Moser, W., Solution to Problem 10, Can. Math. Bull. 4 (1961), 187–189.
Nechushtan, O., On the space chromatic number, Discrete Math. 256 (2002), 499–507.
Nelson, E., Letter to A. Soifer of August 23, 1991.
Nelson, E., Letter to A. Soifer of October 5, 1991.
O’Donnell, P., High girth unit-distance graphs, Ph. D. Dissertation, Rutgers University, May 25, 1999.
O’Donnell, P., Arbitrary girth, 4-chromatic unit-distance graphs in the plane part I: Graph description, Geombinatorics IX(3), (2000), 145–150.
O’Donnell, P., Arbitrary girth, 4-chromatic unit-distance graphs in the plane part II: Graph embedding, Geombinatorics IX(4), (2000), 180–193.
Payne, M. S., A unit distance graph with ambiguous chromatic number, arXiv: 0707.1177v1 [math.CO] 9 Jul 2007.
Payne, M. S., Unit distance graphs with ambiguous chromatic number, Electronic J.Combin. 16(1), 2009 (Nov 7, 2009).
Peter, L. J., Peter’s Quotations: Ideas for Our Time, William Morrow, New York, 1977.
Materialy Konferenzii “Poisk-97”, Moscow, 1997, (Russian).
Pritikin, D., All unit-distance graphs of order 6197 are 6-colorable, J. Combin. Theory Ser. B 73(2), (1998), 159–163.
Radoicic, R., and Tóth, G., Note on the chromatic number of the space, Discrete and Computational Geometry: the Goodman-Pollack Festschrift, B. Aronov, S. Basu, J. Pach, and M. Sharir (eds.), Springer, Berlin 2003, 695–698.
Raigorodskii, A. M., On the chromatic number of a space, Russ. Math. Surv. 55(2), (2000), 351–352.
Raigorodskii, A. M., Borsuk’s problem and the chromatic numbers of some metric spaces, Russian Math. Surv. 56(1), (2001), 103–139.
Raigorodskii, A. M., Chromatic Numbers (Russian), Moscow Center of Continuous Mathematical Education, Moscow, 2003.
Raiskii, D. E., Realizing of all distances in a decomposition of the space R n into n+1 Parts, Mat. Zametki 7 (1970), 319–323 [Russian]; Engl. transl., Math. Notes 7 (1970), 194–196.
Shelah, S., and Soifer, A., Axiom of choice and chromatic number of the Plane, J.Combin. Theory Ser. A 103(2003) 387–391.
Soifer, A., and Shelah, S., Axiom of choice and chromatic number: An example on the plane, J. Combin. Theory Ser. A 105(2), (2004), 359–364.
Simmons, G. J., The chromatic number of the sphere, J. Austral. Math. Soc. Ser. A 21 (1976), 473–480.
Soifer, A., The Mathematical Coloring Book: Mathematics of Coloring and the Colorful Life of Its Creators, Springer, New York, 2009.
Soifer, A., Triangles in a three-colored plane, Geombinatorics I(2) (1991), 11–12 and I(4) (1992), 21.
Soifer, A., Chromatic number of the plane: A historical essay, Geombinatorics I(3), (1991), 13–15.
Soifer, A., Relatives of chromatic number of the plane I, Geombinatorics I(4), (1992), 13–15.
Soifer, A., A six-coloring of the plane, J. Combin. Theory Ser A 61(2), (1992), 292–294.
Soifer, A., Six-realizable set X 6, Geombinatorics III(4), (1994).
Soifer, A., An infinite class of 6-colorings of the plane, Congressus Numerantium 101 (1994), 83–86.
Soifer, A., 50th Anniversary of one problem: Chromatic number of the plane, Mathematics Competitions 16(1), (2003), 9–41.
Soifer, A., Axiom of choice and chromatic number of R n, J. Combin. Theory Ser A 110(1), (2005), 169–173.
Solovay, R. M., A model of set theory in which every set of reals is Lebesgue measurable, Ann. Math. 92 Ser. 2 (1970), 1–56.
Székely, L. A., Remarks on the chromatic number of geometric graphs, in Graphs and Other Combinatorial Topics, Proceedings of the Third Czechoslovak Symposium on Graph Theory, Prague, August 24–27, 1982, M. Fiedler, ed., Teubner Verlaggesellschaft, Leipzig, 1983, 312–315.
Székely, L. A., Measurable chromatic number of geometric graphs and sets without some distances in Euclidean space, Combinatorica 4 (1984) 213–218.
Szekeres, Gy., A combinatorial problem in geometry: Reminiscences, in Paul Erdös, The Art of Counting, MIT Press, Cambridge, MA, 1973, xix–xxii.
Woodall, D. R., Distances realized by sets covering the plane, J. Combin. Theory Ser. A 14 (1973), 187–200.
Wormald, N.C., A 4-chromatic graph with a special plane drawing, J. Austral. Math. Soc. Ser. A 28(1979), 1–8.
Zaks, J., On the chromatic number of some rational spaces, Combin. Optim., Research Report Corr 88–26 (1988), 1–3.
Zaks, J., On four-colourings of the rational four-space, Aequationes Math. 27 (1989) 259–266.
Zaks, J., On the chromatic number of some rational spaces, Ars Combinatorica 33 (1992), 253–256.
Zaks, J., Uniform distances in rational unit-distance graphs, Discrete Math. 109 (1–3), (1992) 307–311.
Zaks, J., On odd integral distances rational graphs, Geombinatorics IX(2), (1999), 90–95.
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Soifer, A. (2011). Chromatic Number of the Plane & Its Relatives, History, Problems and Results: An Essay in 11 Parts . In: Soifer, A. (eds) Ramsey Theory. Progress in Mathematics, vol 285. Birkhäuser, Boston, MA. https://doi.org/10.1007/978-0-8176-8092-3_8
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