On the rotation distance between binary trees
نویسندگان
چکیده
منابع مشابه
On the rotation distance between binary trees
We develop combinatorial methods for computing the rotation distance between binary trees, i.e., equivalently, the flip distance between triangulations of a polygon. As an application, we prove that, for each n, there exist size n trees at distance 2n − O( √ n). If T, T ′ are finite binary rooted trees, one says that T ′ is obtained from T by one rotation if T ′ coincides with T except in the n...
متن کاملRestricted rotation distance between binary trees
Restricted rotation distance between pairs of rooted binary trees measures differences in tree shape and is related to rotation distance. In restricted rotation distance, the rotations used to transform the trees are allowed to be only of two types. Restricted rotation distance is larger than rotation distance, since there are only two permissible locations to rotate, but is much easier to comp...
متن کاملLower bounds on the rotation distance of binary trees
The rotation distance d(S, T ) between two binary trees S, T of n vertices is the minimum number of rotations to transform S into T . While it is known that d(S, T ) ≤ 2n− 6, a well known conjecture states that there are trees for which this bound is sharp for any value of n ≥ 11. We are unable to prove the conjecture, but we give here some simple criteria for lower bound evaluation, leading fo...
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Generalized recoupling coeecients or 3nj-coeecients for a Lie algebra (with su(2), the Lie algebra for the quantum theory of angular momentum, as generic example) can always be expressed as multiple sums over products of Racah coeecients (i.e. 6j-coeecients). In general there exist many such expressions; we say that such an expression is optimal if the number of Racah coeecients in such a produ...
متن کاملAn efficient upper bound of the rotation distance of binary trees
A polynomial time algorithm is developed for computing an upper bound for the rotation distance of binary trees and equivalently for the diagonal-flip distance of convex polygons triangulations. Ordinal tools are used. 2000 Elsevier Science B.V. All rights reserved.
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ژورنال
عنوان ژورنال: Advances in Mathematics
سال: 2010
ISSN: 0001-8708
DOI: 10.1016/j.aim.2009.09.016