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Projective bundles.

Baker, R.D., Brown, J.M.N., Ebert, G.L., Fisher, J.C. (1994)

Bulletin of the Belgian Mathematical Society - Simon Stevin

Proof of a conjecture of Hirschhorn and Sellers on overpartitions

William Y. C. Chen, Ernest X. W. Xia (2014)

Acta Arithmetica

Let p̅(n) denote the number of overpartitions of n. It was conjectured by Hirschhorn and Sellers that p̅(40n+35) ≡ 0 (mod 40) for n ≥ 0. Employing 2-dissection formulas of theta functions due to Ramanujan, and Hirschhorn and Sellers, we obtain a generating function for p̅(40n+35) modulo 5. Using the (p, k)-parametrization of theta functions given by Alaca, Alaca and Williams, we prove the congruence p̅(40n+35) ≡ 0 (mod 5) for n ≥ 0. Combining this congruence and the congruence p̅(4n+3) ≡ 0 (mod...

Proof of a conjectured three-valued family of Weil sums of binomials

Daniel J. Katz, Philippe Langevin (2015)

Acta Arithmetica

We consider Weil sums of binomials of the form W F , d ( a ) = x F ψ ( x d - a x ) , where F is a finite field, ψ: F → ℂ is the canonical additive character, g c d ( d , | F × | ) = 1 , and a F × . If we fix F and d, and examine the values of W F , d ( a ) as a runs through F × , we always obtain at least three distinct values unless d is degenerate (a power of the characteristic of F modulo | F × | ). Choices of F and d for which we obtain only three values are quite rare and desirable in a wide variety of applications. We show that if F is a field of order 3ⁿ with n odd, and d = 3 r + 2 with...

Proper connection number of bipartite graphs

Jun Yue, Meiqin Wei, Yan Zhao (2018)

Czechoslovak Mathematical Journal

An edge-colored graph G is proper connected if every pair of vertices is connected by a proper path. The proper connection number of a connected graph G , denoted by pc ( G ) , is the smallest number of colors that are needed to color the edges of G in order to make it proper connected. In this paper, we obtain the sharp upper bound for pc ( G ) of a general bipartite graph G and a series of extremal graphs. Additionally, we give a proper 2 -coloring for a connected bipartite graph G having δ ( G ) 2 and a dominating cycle...

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