Acta mathematica scientia,Series A ›› 1982, Vol. 2 ›› Issue (1): 105-110.

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LINE COLORED TREES WITH EXTENDABLE AUTOMORPHISMS

Georg Gati1, Frank Harary2, Robert W. Robinson3   

  1. 1. Institut fur Informatik, ETH Zurich, Switzerland;
    2. Churchill College, University of Cambridge, England;
    3. University of Newcastle, New South Wales 2308, Australia
  • Received:1981-10-04 Online:1982-03-26 Published:1982-03-26
  • Supported by:
    Supported by Swiss National Science Foundation Grants Nos. 2

Abstract: An E-tree is a rooted line-colored tree such that every automorphism of a subtree contain-s ing the root can be extended to an automorphism of the entire tree. When only one color i used, E-trees correspond both to achiral planted trees and to partitions with successively divisible parts. The exact numbers of E-trees with n points and colors from a store of c are found, with and without the restriction that each color should be used at least one. Asymptotic formulas for these quantities are discussed for c fixed and n→∞.

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