Abstract
We offer evidence in the disproof of the continuity of the length of minimum inner spanning trees with respect to a parameter vector having a zero component. The continuity property is the key step of the proof of the conjecture in Du and Hwang (Proc. Nat. Acad. Sci. U.S.A. 87:9464–9466, 1990; Algorithmica 7(1):121–135, 1992). Therefore the Steiner ratio conjecture proposed by Gilbert-Pollak (SIAM J. Appl. Math. 16(1):1–29, 1968) has not been proved yet. The Steiner ratio of a round sphere has been discussed in Rubinstein and Weng (J. Comb. Optim. 1:67–78, 1997) by assuming the validity of the conjecture on a Euclidean plane in Du and Hwang (Proc. Nat. Acad. Sci. U.S.A. 87:9464–9466, 1990; Algorithmica 7(1):121–135, 1992). Hence the results in Rubinstein and Weng (J. Comb. Optim. 1:67–78, 1997) have not been proved yet.
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The Research of B.H. Kim was supported by the Korea Research Council of Fundamental Science & Technology (KRCF) Grant No. C-RESEARCH-2006-11 NIMS.
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Innami, N., Kim, B.H., Mashiko, Y. et al. The Steiner Ratio Conjecture of Gilbert-Pollak May Still Be Open. Algorithmica 57, 869–872 (2010). https://doi.org/10.1007/s00453-008-9254-3
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DOI: https://doi.org/10.1007/s00453-008-9254-3