Towards a Generic Trace for Rule Based Constraint Reasoning

CHR is a very versatile programming language that allows programmers to declaratively specify constraint solvers. An important part of the development of such solvers is in their testing and debugging phases. Current CHR implementations support those phases by offering tracing facilities with limited information. In this report, we propose a new trace for CHR which contains enough information to analyze any aspects of \CHRv\ execution at some useful abstract level, common to several implementations. %a large family of rule based solvers. This approach is based on the idea of generic trace. Such a trace is formally defined as an extension of the $\omega_r^\lor$ semantics of CHR. We show that it can be derived form the SWI Prolog CHR trace

Analogies between the crossing number and the tangle crossing number

Tanglegrams are special graphs that consist of a pair of rooted binary trees with the same number of leaves, and a perfect matching between the two leaf-sets. These objects are of use in phylogenetics and are represented with straightline drawings where the leaves of the two plane binary trees are on two parallel lines and only the matching edges can cross. The tangle crossing number of a tanglegram is the minimum crossing number over all such drawings and is related to biologically relevant quantities, such as the number of times a parasite switched hosts. Our main results for tanglegrams which parallel known theorems for crossing numbers are as follows. The removal of a single matching edge in a tanglegram with $n$ leaves decreases the tangle crossing number by at most $n-3$, and this is sharp. Additionally, if $\gamma(n)$ is the maximum tangle crossing number of a tanglegram with $n$ leaves, we prove $\frac{1}{2}\binom{n}{2}(1-o(1))\le\gamma(n)<\frac{1}{2}\binom{n}{2}$. Further, we provide an algorithm for computing non-trivial lower bounds on the tangle crossing number in $O(n^4)$ time. This lower bound may be tight, even for tanglegrams with tangle crossing number $\Theta(n^2)$.Comment: 13 pages, 6 figure

Synergistic mixed-layer height retrieval method using microwave radiometer and lidar ceilometer observations

This paper tackles synergistic mixed-layer height (MLH) estimation via a combination of microwave radiometer (MWR) and lidar ceilometer (LC)-based estimates. While MLH-MWR estimates rely on potential temperature retrievals, MLH-LC estimates rely on aerosol gradients. The pros and cons of MLH retrievals obtained from MWR via the parcel method and from LC via an extended Kalman filter (EKF)-based method are used to motivate the synergistic algorithm. The synergistic algorithm is introduced as a maximum-likelihood combination of MLH-MWR and MLH-LC. Two case examples from the 2013 HOPE campaign at Jülich, Germany, are used to show the robustness of the synergistic method and the effect of surface temperature measurement error. Doppler wind lidar retrievals and radiosonde reference MLH estimates are used for validation.This research is part of the projects PGC2018-094132-B-I00 and MDM-2016-0600 (“CommSensLab” Excellence Unit) funded by Ministerio de Ciencia e Investigación (MCIN)/ Agencia Estatal de Investigación (AEI)/ 10.13039/501100011033/ FEDER. Data were provided by Julich Observatory for Cloud Evolution (JOYCE-CF), a core facility funded by Deutsche Forschungsgemeinschaft via grant DFG LO 901/7-1. The work of M.P.A.S was supported under Grant PRE2018-086054 funded by MCIN/AEI/ 10.13039/501100011033 and FSE “El FSE invierte en tu futuro”. The European Commission collaborated under projects H2020 ACTRIS-IMP (GA871115) and H2020 ATMO-ACCESS (GA-101008004).Peer ReviewedPostprint (author's final draft

"Com a flecha engatilhada” : rap e textualidades indígenas descolonizando as aulas de literatura

Este trabalho é compartilhamento de um processo de pesquisa que propõe a abordagem das literaturas indígenas (em seus diversos suportes) como possibilidades de descolonizar as representações acerca dos povos originários do Brasil quando abordadas em sala de aula. A ideia principal é que assim como a arte, a linguagem é um campo de disputas importantes e também o principal espaço de expressão para diferentes grupos. Sendo assim, proponho que seja possível construir uma discussão sobre essas temáticas nas aulas de Literatura, e fazendo isso podemos transformar muitos dos paradigmas que perpetuam as representações hegemônicas de grupos tachados como minorias, e também evidenciar essas vozes que combatem as estruturas coloniais que se renovam ainda hoje no nosso país. Partindo do pressuposto de que o os movimentos que se colocam frente à essa organização opressora empreendem atitudes anticoloniais (ou decoloniais), e que isso acontece por meio de processos pedagógicos (WALSH, 2005), proponho uma forma de abordar as produções de sujeitos indígenas (e em especial de jovens Guarani Mbyá e Kaiowá que produzem Rap), que evidencie seu potencial pedagógico. Ou seja, neste trabalho além de brevemente discutir as formas das textualidades indígenas no Brasil, apresento também uma discussão sobre o ensino de Literatura através do relato de duas experiências práticas (a construção de um projeto sobre linguagens, juventudes indígenas e resistência, pensado para alunos de Ensino Médio, e o relato de duas atividades desenvolvidas no Coletivo de Educação Território Popular), que podem auxiliar na compreensão e difusão dessas produções, e sobretudo servem em parte como exemplo de como se dão os processos de desaprendizagens das formas coloniais e reaprendizagem em ambientes mais coletivos e horizontais.Este trabajo es una forma de compartir el proceso de investigación que propone el abordaje de las literaturas indígenas (en sus variados soportes) como posibilidades de descolonizar las representaciones de los pueblos originarios de Brasil cuando son abordadas en clase. La idea principal es que, así como el arte, el lenguaje es un campo de disputas importantes y también el principal espacio de expresión para diferentes grupos. Igualmente, propongo que sea posible construir una discusión sobre esas temáticas en las clases de Literatura, y, con eso, transformar muchos de los paradigmas que perpetúan las representaciones hegemónicas de grupos tachados de minorías, y también evidenciar esas voces que combaten las estructuras coloniales que se renuevan todavía hoy en nuestro país. Partiendo de la hipótesis de que los movimientos que se plantean frente a esa organización opresora emprenden actitudes anticoloniales (o decoloniales), y que eso ocurre a través de procesos pedagógicos (WALSH, 2005), presento una forma de abordar las producciones de sujetos indígenas (en especial jóvenes Guaraní Mbyá y Kaiowá que producen Rap), que señale su potencial pedagógico. En este trabajo, además de brevemente discutir las formas de las textualidades indígenas en Brasil, presento también una discusión sobre la enseñanza de Literatura a través del relato de dos experiencias prácticas (la construcción de un proyecto sobre lenguajes, juventudes indígenas y resistencia, pensado para alumnos de enseñanza secundaria, y el relato de dos actividades desarrolladas en el Coletivo de Educação Território Popular), que pueden auxiliar en la comprensión y difusión de esas producciones, y, sobretodo, sirven en parte como ejemplo de cómo se construyen los de desaprendizajes de las formas coloniales y reaprendizaje en ambientes más colectivos y hori procesos zontales

Dwarf elliptical galaxies in Centaurus A group: stellar populations in AM 1339-445 and AM 1343-452

We study the red giant populations of two dE galaxies, AM 1339-445 and AM 1343-452, with the aim of investigating the number and luminosity of any upper asymptotic giant branch (AGB) stars present. The galaxies are members of the Centaurus A group (D~3.8 Mpc) and are classified as outlying (R~350 kpc) satellites of Cen A. The analysis is based on near-IR photometry for individual red giant stars, derived from images obtained with ISAAC on the VLT. The photometry, along with optical data derived from WFPC2 images retrieved from the HST science archive, enable us to investigate the stellar populations of the dEs in the vicinity of the red giant branch (RGB) tip. In both systems we find stars above the RGB tip, which we interpret as intermediate-age upper-AGB stars. The presence of such stars is indicative of extended star formation in these dEs similar to that seen in many, but not all, dEs in the Local Group. For AM 1339-445, the brightest of the upper-AGB stars have Mbol~-4.5 while those in AM 1343-452 have Mbol~-4.8 mag. These luminosities suggest ages of approximately 6.5+/-1 and 4+/-1 Gyr as estimates for the epoch of the last episode of significant star formation in these systems. In both cases the number of upper-AGB stars suggests that ~15% of the total stellar population is in the form of intermediate-age stars, considerably less than is the case for outlying dE satellites of the Milky Way such as Fornax and LeoI.Comment: 18 pages, 19 figures, A&A accepted; high resolution version available from: http://www.eso.org/~mrejkuba/CenA_dEs_I.pd

A taxonomy of small Markovian errors

Errors in quantum logic gates are usually modeled by quantum process matrices (CPTP maps). But process matrices can be opaque, and unwieldy. We show how to transform a gate's process matrix into an error generator that represents the same information more usefully. We construct a basis of simple and physically intuitive elementary error generators, classify them, and show how to represent any gate's error generator as a mixture of elementary error generators with various rates. Finally, we show how to build a large variety of reduced models for gate errors by combining elementary error generators and/or entire subsectors of generator space. We conclude with a few examples of reduced models, including one with just $9N^2$ parameters that describes almost all commonly predicted errors on an N-qubit processor.Comment: 18 pages, 12 figures, all the customized error models you could ever wan

Stellar over-densities in the halo: the extent of the Virgo over-density

We map the three dimensional extent of the Virgo Over-density by combining distance information from RR Lyrae variables and projected spatial information from SEKBO (Keller et al. 2008) and Sloan Digital Sky Survey (SDSS) DR6 photometry. The Virgo Over-density is seen to comprise two filaments 14.5 x 3 degrees and 10 x 3 degrees and a circular structure 3 degrees in diameter. Together the three features span 38 degrees of right ascension and declinations of +2 to -15 degrees. RR Lyrae variables place the two filamentary features at heliocentric distances of 20 and 17 kpc respectively, with projected dimensions of 5 x 1 kpc and 3 x 1 kpc.Comment: 6 pages, 5 figures, MNRAS accepte