988 resultados para Maximal unipotent subgroups
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We investigate the NP-complete problem Vertex Separation (VS) on Maximal Outerplanar Graphs (mops). We formulate and prove a “main theorem for mops”, a necessary and sufficient condition for the vertex separation of a mop being k. The main theorem reduces the vertex separation of mops to a special kind of stretchability, one that we call affixability, of submops.
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A subgroup H of a group G is said to be quasinormal if HX = XH for all subgroups X of G. In this article groups are characterized for which the partially ordered set of quasinormal subgroups is decomposable.
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We characterize the groups which do not have non-trivial perfect sections and such that any strictly descending chain of non-“nilpotent-by-finite” subgroups is finite.
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2000 Mathematics Subject Classification: Primary 42B20; Secondary 42B15, 42B25
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2000 Mathematics Subject Classification: 42B20, 42B25, 42B35
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2000 Mathematics Subject Classification: Primary 20C07, 20K10, 20K20, 20K21; Secondary 16U60, 16S34.
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2000 Mathematics Subject Classification: 49J40, 49J35, 58E30, 47H05
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2000 Mathematics Subject Classification: 05C35.
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2000 Mathematics Subject Classification: 20E18, 12G05, 12F10, 12F99.
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2000 Mathematics Subject Classification: 16R10, 16R30.