#### Filter Results:

- Full text PDF available (6)

#### Publication Year

2006

2017

- This year (1)
- Last 5 years (4)
- Last 10 years (7)

#### Publication Type

#### Co-author

#### Journals and Conferences

#### Key Phrases

Learn More

- Rigoberto Flórez, David Forge
- J. Comb. Theory, Ser. A
- 2007

The study of non-orientable matroids has not received very much attention compared with the study of representable matroids or oriented matroids. Proving non-orientability of a matroid is known to be a difficult problem even for small matroids of rank 3. RichterGebert [4] even proved that this problem is NP-complete. In general, there are only some… (More)

The Hosoya polynomial triangle is a triangular arrangement of polynomials where each entry is a product of two polynomials. The geometry of this triangle is a good 1 tool to study the algebraic properties of polynomial products. In particular, we find closed formulas for the alternating sum of products of polynomials such as Fibonacci polynomials, Chebyshev… (More)

The generalized Hosoya triangle is an arrangement of numbers where each entry is a product of two generalized Fibonacci numbers. We define a discrete convolution 1 C based on the entries of the generalized Hosoya triangle. We use C and generating functions to prove that the sum of every k-th entry in the n-th row or diagonal of generalized Hosoya triangle,… (More)

- Rigoberto Flórez
- Discrete Mathematics
- 2009

- Éva Czabarka, Rigoberto Flórez, Leandro Junes
- Electr. J. Comb.
- 2015

We construct a formal power series on several variables that encodes many statistics on non-decreasing Dyck paths. In particular, we use this formal power series to count peaks, pyramid weights, and indexed sums of pyramid weights for all nondecreasing Dyck paths of length 2n. We also show that an indexed sum on pyramid weights depends only on the size and… (More)

- Rigoberto Flórez
- Eur. J. Comb.
- 2006

Gordon introduced a class of matroids M(n), for prime n ≥ 2, such that M(n) is algebraically representable, but only in characteristic n. Lindström proved that M(n) for general n ≥ 2 is not algebraically representable if n > 2 is an even number, and he conjectured that if n is a composite number it is not algebraically representable. We introduce a new kind… (More)

We study a relation between factorials and their additive analog, the triangular numbers. We show that there is a positive integer k such that n! = 2kT where T is a product of triangular numbers. We discuss the primality of T±1 and the primality of |T − p| where p is either the smallest prime greater than T or the greatest prime less than T .

- Ruth Lopez, Jacob Worrell, Henry Wickus, Rigoberto Flórez, Darren A. Narayan
- Australasian J. Combinatorics
- 2017

In a social network individuals have prominent centrality if they are intermediaries between the communication of others. The betweenness centrality of a vertex measures the number of intersecting geodesics between two other vertices. Formally, the betweenness centrality of a vertex v is the ratio of the number of shortest paths between two other vertices u… (More)

- ‹
- 1
- ›