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A Note on Counting Homomorphisms of Paths
被引:1
|作者:
Eggleton, Roger B.
[1
]
Morayne, Michal
[2
]
机构:
[1] Illinois State Univ, Dept Math, Normal, IL 61790 USA
[2] Wroclaw Univ Technol, Inst Math & Comp Sci, PL-50370 Wroclaw, Poland
关键词:
Path;
Homomorphism;
Generating function;
Catalan number;
Endomorphism;
ALGORITHM;
NUMBER;
D O I:
10.1007/s00373-012-1261-0
中图分类号:
O1 [数学];
学科分类号:
0701 ;
070101 ;
摘要:
We obtain two identities and an explicit formula for the number of homomorphisms of a finite path into a finite path. For the number of endomorphisms of a finite path these give over-count and under-count identities yielding the closed-form formulae of Myers. We also derive finite Laurent series as generating functions which count homomorphisms of a finite path into any path, finite or infinite.
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页码:159 / 170
页数:12
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