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81.
Aleš Drápal 《Monatshefte für Mathematik》2002,134(3):191-206
Several new tools are developed dealing with multiplication groups of loops. One of them is based upon the theorem that the
inner mapping group of a loop never acts faithfully on any of its orbits, unless it is trivial. The applications include an
analysis of loops whose inner mapping group is nonabelian of order pq. Some important earlier results are proved anew in a shorter way.
(Received 5 March 2001; in revised form 11 June 2001) 相似文献
82.
The paper is concerned with several related combinatorial problems one of which is that of estimating the numbers of qualitatively independent p-partitions. Besides nonconstructive basic estimates, a constructive procedure yielding not much worse ones is presented. In conclusion, some applications are shown. 相似文献
83.
84.
Aleš Pultr 《Mathematische Annalen》1968,178(1):78-82
Ohne ZusammenfassungUnterstützt von der Alexander von Humboldt-Stiftung. 相似文献
85.
The classes of relations and graphs determined by subobjects and factorobjects are studied. We investigate whether such classes are closed under products, whether they are finitely generated by products and subobjects and whether a class can be described alternatively by subobjects and factorobjects. This is related to good characterizations. 相似文献
86.
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89.
Resonant Homoclinic Flip Bifurcations 总被引:6,自引:0,他引:6
This paper studies three-parameter unfoldings of resonant orbit flip and inclination flip homoclinic orbits. First, all known results on codimension-two unfoldings of homoclinic flip bifurcations are presented. Then we show that the orbit flip and inclination flip both feature the creation and destruction of a cusp horseshoe. Furthermore, we show near which resonant flip bifurcations a homoclinic-doubling cascade occurs. This allows us to glue the respective codimension-two unfoldings of homoclinic flip bifurcations together on a sphere around the central singularity. The so obtained three-parameter unfoldings are still conjectural in part but constitute the simplest, consistent glueings. 相似文献
90.
Miroslav Novák Marek Bouška Dr. Libor Dostál Dr. Aleš Růžička Dr. Alexander Hoffmann Prof. Dr. Sonja Herres‐Pawlis Dr. Roman Jambor 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(21):7820-7829
We report here the synthesis of new C,N‐chelated chlorostannylenes and germylenes L3MCl (M=Sn( 1 ), Ge ( 2 )) and L4MCl (M=Sn( 3 ), Ge ( 4 )) containing sterically demanding C,N‐chelating ligands L3, 4 (L3=[2,4‐di‐tBu‐6‐(Et2NCH2)C6H2]?; L4=[2,4‐di‐tBu‐6‐{(C6H3‐2′,6′‐iPr2)N=CH}C6H2]?). Reductions of 1 – 4 yielded three‐coordinate C,N‐chelated distannynes and digermynes [L3, 4M ]2 for the first time ( 5 : L3, M=Sn, 6 : L3, M=Ge, 7 : L4, M=Sn, 8 : L4, M=Ge). For comparison, the four‐coordinate distannyne [L5Sn]2 ( 10 ) stabilized by N,C,N‐chelate L5 (L5=[2,6‐{(C6H3‐2′,6′‐Me2)N?CH}2C6H3]?) was prepared by the reduction of chlorostannylene L5SnCl ( 9 ). Hence, we highlight the role of donor‐driven stabilization of tetrynes. Compounds 1 – 10 were characterized by means of elemental analysis, NMR spectroscopy, and in the case of 1 , 2 , 5 – 7 , and 10 , also by single‐crystal X‐ray diffraction analysis. The bonding situation in either three‐ or four‐coordinate distannynes 5 , 7 , and 10 was evaluated by DFT calculations. DFT calculations were also used to compare the nature of the metal–metal bond in three‐coordinate C,N‐chelating distannyne [L3Sn]2 ( 5 ) and related digermyme [L3Ge]2 ( 6 ). 相似文献