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Daniel Camazón

Publications and source records attributed to Daniel Camazón.

2 recordsLinked to original sources

Sequences of point blow-ups over perfect fields from a combinatorial point of view

We associate a combinatorial object to sequences of point blow-ups over perfect fields, the weighted directed graph, and another one to the composition of all blow-ups, which we call associated sequential morphisms, the $d-$ary intersection form. Then, in order to consider different fields extensions, we introduce the concepts of algebraically and combinatorially compatible partitions of the exceptional divisor for both sequences of point blow-ups and sequential morphisms, which lead us to define the corresponding algebraic and combinatorial equivalence classes. We prove that there exists a bijection between the respective combinatorial equivalence classes of sequences of point blow-ups and the associated sequential morphisms, and moreover, we also give a proof of the existence of a suitable bijection between the respective algebraic equivalence classes.

math.AG↗

On the solutions of linear systems over additively idempotent semirings

The aim of this article is to solve the system $XA=Y$ where $A=(a_{ij})\in M_{m\times n}(S)$, $Y\in S^{m}$ and $X$ is an unknown vector of size $n$, being $S$ an additively idempotent semiring. If the system has solutions then we completely characterize its maximal one, and in the particular case where $S$ is a generalized tropical semiring a complete characterization of its solutions is provided as well as an explicit bound of the computational cost associated to its computation. Finally, when $S$ is finite, we give a cryptographic application by presenting an attack to the key exchange protocol proposed by Maze, Monico and Rosenthal.

cs.IT↗