Two novel evolutionary formulations of the graph coloring problem

We introduce two novel evolutionary formulations of the problem of coloring the nodes of a graph. The first formulation is based on the relationship that exists between a graph's chromatic number and its acyclic orientations. It views such orientations as individuals and evolves them with the aid of evolutionary operators that are very heavily based on the structure of the graph and its acyclic orientations. The second formulation, unlike the first one, does not tackle one graph at a time, but rather aims at evolving a `program' to color all graphs belonging to a class whose members all have the same number of nodes and other common attributes. The heuristics that result from these formulations have been tested on some of the Second DIMACS Implementation Challenge benchmark graphs, and have been found to be competitive when compared to the several other heuristics that have also been tested on those graphs.Comment: To appear in Journal of Combinatorial Optimizatio

Modeling the input history of programs for improved instruction-memory performance

When a program is loaded into memory for execution, the relative position of its basic blocks is crucial, since loading basic blocks that are unlikely to be executed first places them high in the instruction-memory hierarchy only to be dislodged as the execution goes on. In this paper we study the use of Bayesian networks as models of the input history of a program. The main point is the creation of a probabilistic model that persists as the program is run on different inputs and at each new input refines its own parameters in order to reflect the program's input history more accurately. As the model is thus tuned, it causes basic blocks to be reordered so that, upon arrival of the next input for execution, loading the basic blocks into memory automatically takes into account the input history of the program. We report on extensive experiments, whose results demonstrate the efficacy of the overall approach in progressively lowering the execution times of a program on identical inputs placed randomly in a sequence of varied inputs. We provide results on selected SPEC CINT2000 programs and also evaluate our approach as compared to the gcc level-3 optimization and to Pettis-Hansen reordering

Alstroemeriaceae na região Sul do Brasil.

Resumo: Alstroemeriaceae compreende ervas perenes eretas ou volúveis, rizomatosas de folhas geralmente ressupinadas. É encontrada em quase todos os tipos de hábitats, de florestas a brejos e até desertos. A família está representada na Região Sul do Brasil pelo gênero Alstroemeria L., incluindo 9 espécies: Alstroemeria albescens M.C.Assis, A. amabilis M.C.Assis, A. apertiflora Baker, A. cunha Vell., A. inodora Herb., A. isabelleana Herb., A. malmeana Kraenzl., A. psittacina Lehm., A. sellowiana Seub. ex Schenk, e pelo gênero Bomarea Mirb. incluindo apenas a espécie B. edulis (Tussac) Herb. Neste trabalho são apresentadas nova sinonimização, chaves de identificação, descrição das espécies, ilustrações e comentários. Palavras-chave: Alstroemeria, Bomarea, flora, sistemática, Brasil Abstract: Alstroemeriaceae comprises perennial herbs that are erect or twining and rhizomatous. The leaves are generally resupinate. They are found in a wide range of habitats including cloud forests, swamps and desert areas. The family is represented at South of Brazil by 2 genus: Alstroemeria L. and Bomarea Mirb. Alstroemeria included 9 species: Alstroemeria albescens M.C.Assis, A. amabilis M.C.Assis, A. apertiflora Baker, A. cunha Vell., A. inodora Herb., A. isabelleana Herb., A. malmeana Kraenzl., A. psittacina Lehm., A. sellowiana Seub. ex Schenk. Bomarea included just one specie, B. edulis (Tussac) Herb. New synonym, key to genera and species, descriptions, illustrations and comments are presented

New species of Alstroemeria altroemeriaceae from the Brazilian Savannas.

Two new species of Alstroemeria (Alstroemeriaceae) from the Brazilian savannas are described: A. stenophylla M. C. Assis, which is characterized by its narrow linear-lanceolate leaves, concentrated on the distal region of the vegetative stem, and for its ruby-spotted inner tepals, close to A. gardneri Baker and A. plantaginea Martiuse x Schultes & Schultesf .; and A . tombolatoana M. C. Assis, which may be recognized by its coriaceous leaves, outer tepals oblong-spatulate, without patterning, but the inner tepals spatulate and ruby-maculates, sympatric with A. gardneri. Descriptions, comments, and illustrations are presented