Modeling Universal Instruction Selection

Instruction selection implements a program under compilation by selecting  processor instructions and has tremendous impact on the performance of the  code generated by a compiler. This paper introduces a graph-based  universal representation that unifies data and control flow for both  programs and processor instructions. The representation is the essential  prerequisite for a constraint model for instruction selection introduced in  this paper. The model is demonstrated to be expressive in that it supports many processor  features that are out of reach of state-of-the-art approaches, such as  advanced branching instructions, multiple register banks, and SIMD  instructions. The resulting model can be solved for small to medium size  input programs and sophisticated processor instructions and is competitive with LLVM in code quality. Model and representation are significant due to their  expressiveness and their potential to be combined with models for other code  generation tasks.QC 20150828</p

Integrating Operations Research in Constraint Programming

This paper presents constraint programming (CP) as a natural formalism for modelling problems, and as a flexible platform for solving them. CP has a range of techniques for handling constraints including several forms of propagation and tailored algorithms for global constraints. It also allows linear programming to be combined with propagation and novel and varied search techniques which can be easily expressed in CP. The paper describes how CP can be used to exploit linear programming within different kinds of hybrid algorithm. In particular it can enhance techniques such as Lagrangian relaxation, Benders decomposition and column generation

Nitrogen assimilation in Citrus based on CitEST data mining

Assimilation of nitrate and ammonium are vital procedures for plant development and growth. From these primary paths of inorganic nitrogen assimilation, this metabolism integrates diverse paths for biosynthesis of macromolecules, such as amino acids and nucleotides, and the central intermediate metabolism, like carbon metabolism and photorespiration. This paper reports research performed in the CitEST (Citrus Expressed Sequence Tag) database for the main genes involved in nitrogen metabolism and those previously described in other organisms. The results show that a complete cluster of genes involved in the assimilation of nitrogen and the metabolisms of glutamine, glutamate, aspartate and asparagine can be found in the CitEST data. The main enzymes found were nitrate reductase (NR), nitrite reductase (NiR), glutamine synthetase (GS), glutamate synthetase (GOGAT), glutamate dehydrogenase (GDH), aspartate aminotransferase (AspAT) and asparagine synthetase (AS). The different enzymes involved in this metabolism have been shown to be highly conserved among the Citrus and Poncirus species. This work serves as a guide for future functional analysis of these enzymes in citrus