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61.
62.
If X is a set, R a ring and M an R-module, then it is shown that the R-module of all M-valued functions on X taking on X only finitely many values is free over R. This result is applied to show that inductive limits of finitely generated free R-modules are free over R, provided that the mappings of the inductive system are of a certain diagonal type. No restrictions are placed on the index set. There is a dual statement for projective limits. Among other applications it is shown that the -1st Borel-Moore homology group (with values in any sheaf over an arbitrary integral domain and taken with respect to any paracompactifying family of supports) of a locally compact space vanishes. 相似文献
63.
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65.
Summary 0-1-sequences are constructed by successive insertion of a periodic sequence of symbols 0, 1 and hole into the holes of the sequence already constructed. Assuming that finally all holes are filled with symbols 0, 1, an almost periodic point in shift space results. Under certain conditions, it is even strictly ergodic. It is proved that the attached invariant measure has pure point spectrum, and a rather explicit expression for eigenvectors is obtained. 相似文献
66.
Higham LJ Kelly PG Corr DM Müller-Bunz H Walker BJ Gilheany DG 《Chemical communications (Cambridge, England)》2004,(6):684-685
The Ramirez ylide undergoes electrophilic substitution with acetylenedicarboxylates to form Z and E adducts. The latter can react by cycloaddition with another equivalent of the alkyne to provide a new route to novel tetra-substituted azulenes, which show interesting bond localisation and crystal packing effects. 相似文献
67.
Eoin Rafter Jimmy Muldoon Helge Müller Bunz Declan G. Gilheany 《Tetrahedron: Asymmetry》2011,22(16-17):1680-1686
A synthetic route to BINAP disulfide analogues with chirality on one of the phosphorus atoms was developed. The synthesis of these ligands was achieved by step-wise palladium and nickel-catalysed coupling reactions of the precursor binaphthyl triflate with secondary phosphines and phosphine oxides, respectively. C2-Unsymmeric BINAP bissulfide analogues with the same aryl substituents were also synthesized for the sake of comparison. Preliminary studies of the reduction of these sulfides to the free phosphines are also described. 相似文献
68.
We find necessary and sufficient conditions for a symbolic dynamical system to be topologically conjugate to any given constant length substitution minimal system, thus extending the results in Coven et al. (2008) for the Morse and Toeplitz substitutions. 相似文献
69.
Declan Mungovan Enda Howley Jim Duggan 《Computational & Mathematical Organization Theory》2011,17(2):152-178
In this paper we explore the effect that random social interactions have on the emergence and evolution of social norms in
a simulated population of agents. In our model agents observe the behaviour of others and update their norms based on these
observations. An agent’s norm is influenced by both their own fixed social network plus a second random network that is composed
of a subset of the remaining population. Random interactions are based on a weighted selection algorithm that uses an individual’s
path distance on the network to determine their chance of meeting a stranger. This means that friends-of-friends are more
likely to randomly interact with one another than agents with a higher degree of separation. We then contrast the cases where
agents make highest utility based rational decisions about which norm to adopt versus using a Markov Decision process that
associates a weight with the best choice. Finally we examine the effect that these random interactions have on the evolution
of a more complex social norm as it propagates throughout the population. We discover that increasing the frequency and weighting
of random interactions results in higher levels of norm convergence and in a quicker time when agents have the choice between
two competing alternatives. This can be attributed to more information passing through the population thereby allowing for
quicker convergence. When the norm is allowed to evolve we observe both global consensus formation and group splintering depending
on the cognitive agent model used. 相似文献
70.
Iltaf?Shah Andrea?Petroczi Martina?Uvacsek Márta?Ránky Declan?P?NaughtonEmail author 《Chemistry Central journal》2014,8(1):73