6,975 research outputs found
Topological Complexity is a Fibrewise L-S Category
Topological complexity \TC{B} of a space is introduced by M. Farber to
measure how much complex the space is, which is first considered on a
configuration space of a motion planning of a robot arm. We also consider a
stronger version \TCM{B} of topological complexity with an additional
condition: in a robot motion planning, a motion must be stasis if the initial
and the terminal states are the same. Our main goal is to show the equalities
\TC{B} = \catBb{\double{B}}+1 and \TCM{B} = \catBB{\double{B}}+1, where
\double{B}=B{\times}B is a fibrewise pointed space over whose projection
and section are given by p_{\double{B}}=\proj_{2} : B{\times}B \to B the
canonical projection to the second factor and s_{\double{B}}=\Delta_{B} : B
\to B{\times}B the diagonal. In addition, our method in studying fibrewise L-S
category is able to treat a fibrewise space with singular fibres.
Recently, we found a problem with the proof of Theorem 1.13 which states that
for a fibrewise well-pointed space XB\catBB{X} =
\catBb{X} and that for a locally finite simplicial complex , we have
\TC{B} = \TCM{B}. While we still conjecture that Theorem 1.13 is true, this
problem means that, at present, no proof is given to exist. Alternatively, we
show the difference between two invariants \catBb{X} and \catBB{X} is at
most 1 and the conjecture is true for some cases. We give further corrections
mainly in the proof of Theorem 1.12.Comment: 12pages original + 5pages errat
Splitting off Rational Parts in Homotopy Types
It is known algebraically that any abelian group is a direct sum of a
divisible group and a reduced group (See Theorem 21.3 of
\cite{Fuchs:abelian-group}). In this paper, conditions to split off rational
parts in homotopy types from a given space are studied in terms of a variant of
Hurewicz map, say \bar{\rho} : [S_{\Q}^{n},X] \to H_n(X;\Z) and generalized
Gottlieb groups. This yields decomposition theorems on rational homotopy types
of Hopf spaces, -spaces and Gottlieb spaces, which has been known in various
situations, especially for spaces with finiteness conditions.Comment: 6 page
Co-H-spaces and almost localization
Apart from simply-connected spaces, a non simply-connected co-H-space is a
typical example of a space X with a co-action of along the classifying map of the universal covering. If such
a space X is actually a co-H-space, then the fibrewise p-localization of
(or the `almost' p-localization of X) is a fibrewise co-H-space (or an `almost'
co-H-space, resp.) for every prime p. In this paper, we show that the converse
statement is true, i.e., for a non simply-connected space X with a co-action of
along , X is a co-H-space if, for every prime p, the almost
p-localization of X is an almost co-H-space.Comment: 10 pages, no figure
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