Displaying 321 – 340 of 378

Showing per page

The cubic mapping graph for the ring of Gaussian integers modulo n

Yangjiang Wei, Jizhu Nan, Gaohua Tang (2011)

Czechoslovak Mathematical Journal

The article studies the cubic mapping graph Γ ( n ) of n [ i ] , the ring of Gaussian integers modulo n . For each positive integer n > 1 , the number of fixed points and the in-degree of the elements 1 ¯ and 0 ¯ in Γ ( n ) are found. Moreover, complete characterizations in terms of n are given in which Γ 2 ( n ) is semiregular, where Γ 2 ( n ) is induced by all the zero-divisors of n [ i ] .

The fundamental constituents of iteration digraphs of finite commutative rings

Jizhu Nan, Yangjiang Wei, Gaohua Tang (2014)

Czechoslovak Mathematical Journal

For a finite commutative ring R and a positive integer k 2 , we construct an iteration digraph G ( R , k ) whose vertex set is R and for which there is a directed edge from a R to b R if b = a k . Let R = R 1 ... R s , where s > 1 and R i is a finite commutative local ring for i { 1 , ... , s } . Let N be a subset of { R 1 , , R s } (it is possible that N is the empty set ). We define the fundamental constituents G N * ( R , k ) of G ( R , k ) induced by the vertices which are of the form { ( a 1 , , a s ) R : a i D ( R i ) if R i N , otherwise a i U ( R i ) , i = 1 , ... , s } , where U ( R ) denotes the unit group of R and D ( R ) denotes the zero-divisor set of R . We investigate...

The Lucas congruence for Stirling numbers of the second kind

Roberto Sánchez-Peregrino (2000)

Acta Arithmetica

0. Introduction. The numbers introduced by Stirling in 1730 in his Methodus differentialis [11], subsequently called “Stirling numbers” of the first and second kind, are of the greatest utility in the calculus of finite differences, in number theory, in the summation of series, in the theory of algorithms, in the calculation of the Bernstein polynomials [9]. In this study, we demonstrate some properties of Stirling numbers of the second kind similar to those satisfied by binomial coefficients; in...

Currently displaying 321 – 340 of 378