Image TOPICS
Image
Search

Map Folding


Map folding is the problem of counting distinct ways to fold an m×n rectangular map into a stack one cell wide. A distinct folding is defined by the permutation of its N=mn numbered cells read from the top down. A general formula for the count is not known. Lunnon (1971) tabulates strip counts through n=28.

kOEISk×1, k×2, ...
1A0001361, 2, 6, 16, 50, 144, 462, 1392, ...
2A0014152, 8, 60, 320, 1980, 10512, ...

The number of ways to fold an n×n map is given for n=1, 2, ... by 1, 8, 1368, 300608, 186086600, ... (Lunnon 1971; OEIS A001418).

Let F_n count the foldings of a 1×n strip. The growth rate

 lambda=lim_(n->infty)F_n^(1/n)

exists (Legendre 2014). Gardner (1983) reports the bounds 3.3868<=lambda<=3.9821 from unpublished work of Lunnon. Convergence of the successive ratio F_(n+1)/F_n to lambda follows under the conjectured asymptotic form F_n∼Kn^alphalambda^n (Legendre 2014).


See also

Stamp Folding Problem

Explore with Wolfram|Alpha

References

Gardner, M. "The Combinatorics of Paper Folding." Ch. 7 in Wheels, Life, and Other Mathematical Amusements. New York: W. H. Freeman, pp. 60-73, 1983.Koehler, J. E. "Folding a Strip of Stamps." J. Combin. Th. 5, 135-152, 1968.Legendre, S. "Foldings and Meanders." Austral. J. Combin. 58, 275-291, 2014. https://ajc.maths.uq.edu.au/pdf/58/ajc_v58_p275.pdf.Lunnon, W. F. "A Map-Folding Problem." Math. Comput. 22, 193-199, 1968.Lunnon, W. F. "Multi-Dimensional Strip Folding." Computer J. 14, 75-79, 1971.Sloane, N. J. A. Sequences A000136/M1614, A001415/M1891, and A001418/M4587 in "The On-Line Encyclopedia of Integer Sequences."Wells, M. B. Elements of Combinatorial Computing. Oxford, England: Pergamon Press, p. 238, 1971.

Referenced on Wolfram|Alpha

Map Folding

Cite this as:

Weisstein, Eric W. "Map Folding." From MathWorld--A Wolfram Resource. https://mathworld.wolfram.com/MapFolding.html

Subject classifications