188 citations · 1.3k across the 84 of their papers we have counts for
7 papers · 1 filter
Generating series and matrix models for meandric systems with one shallow side
Motohisa Fukuda, Ion Nechita
In this article, we investigate meandric systems having one shallow side: the arch configuration on that side has depth at most two. This class of meandric systems was introduced a…
Almost Hadamard matrices with complex entries
Teodor Banica, Ion Nechita
We discuss an extension of the almost Hadamard matrix formalism, to the case of complex matrices. Quite surprisingly, the situation here is very different from the one in the real…
Enumerating meandric systems with large number of loops
Motohisa Fukuda, Ion Nechita
We investigate meandric systems with a large number of loops using tools inspired by free probability. For any fixed integer , we express the generating function of meandric sys…
Submatrices of Hadamard matrices: complementation results
Teo Banica, Ion Nechita, Jean-Marc Schlenker
Two submatrices of a Hadamard matrix are called complementary if, up to a permutation of rows and columns, . We find here an explicit formula for the po…
Analytic aspects of the circulant Hadamard conjecture
Teodor Banica, Ion Nechita, Jean-Marc Schlenker
We investigate the problem of counting the real or complex Hadamard matrices which are circulant, by using analytic methods. Our main observation is the fact that for $|q_0|=...=|q…
Almost Hadamard matrices: the case of arbitrary exponents
Teodor Banica, Ion Nechita
In our previous work, we introduced the following relaxation of the Hadamard property: a square matrix is called "almost Hadamard" if is orthog…
Almost Hadamard matrices: general theory and examples
Teodor Banica, Ion Nechita, Karol Zyczkowski
We develop a general theory of "almost Hadamard matrices". These are by definition the matrices having the property that is orthogonal, and is…