ACTA MATHEMATICA UNIVERSITATIS COMENIANAE

ACTA MATHEMATICA UNIVERSITATIS COMENIANAE

Vol. 61, 1 (1992)
pp. 69-84

FRONT-DIVISORS OF TREES
P. HIC, R. NEDELA and S. PAVLIKOVA

Abstract. Generalizing the concept of graph covering we introduce the notion of semicovering of graphs. We prove that the relationship between front-divisors of graph $G$ and semicoverings defined on $G$ has the same character as the well-known relationship between divisors and coverings. Main attention is paid on trees. We show that each front-divisor of a tree $T$ may be obtained by factoring $T$ under any appropriate subgroup of the automorphism group Aut\,$T$.

AMS subject classification. 05C50; Secondary 05C10, 05C25
Keywords. Front-divisor, equitable partition, characteristic polynomial, covering projection, tree

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Acta Mathematica Universitatis Comenianae
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