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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Combinatorica 8 (1988), S. 217-234 
    ISSN: 1439-6912
    Keywords: 05 B 35 ; 05 c 20 ; 68 Q 20
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract LetG be a 2-connected rooted graph of rankr andA, B two (rooted) spanning trees ofG We show that the maximum number of exchanges of leaves that can be required to transformA intoB isr 2−r+1 (r〉0). This answers a question by L. Lovász. There is a natural reformulation of this problem in the theory ofgreedoids, which asks for the maximum diameter of the basis graph of a 2-connected branching greedcid of rankr. Greedoids are finite accessible set systems satisfying the matroid exchange axiom. Their theory provides both language and conceptual framework for the proof. However, it is shown that for general 2-connected greedoids (not necessarily constructed from branchings in rooted graphs) the maximum diameter is 2r−1.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Clinical rheumatology 6 (1987), S. 597-599 
    ISSN: 1434-9949
    Keywords: Multiple Myeloma ; Osteonecrosis ; Spine ; Radiotherapy ; Vacuum Phenomenon
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Authors report one case of intravertebral vacuum phenomenon associated with a multiple myeloma. Initially, there occurred a collapse and a lysis of the L4 vertebral body. Two months later, after chemotherapy and cobalt-therapy, X-ray examination showed a vacuum cleft phenomenon within the body of L4 and a backward displacement of the L4 posterior wall. At the same time the patient complained of a cruralgia. Recovery occurred after decompression surgery. Histologic sampling of the L4 vertebral body revealed bone necrosis without any abnormal plasmocytosis. Authors draw attention to the neurological complications occurring in the course of the vertebral necrosis and to the fact that, even in case of multiple myeloma, the occurrence of a transverse vacuum cleft may result from osteonecrosis.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
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