On the unity of logic

AbstractNous présentons un calcul des séquents unifié, commun aux logiques classique, intuitionniste et linéaire. La principale nouveautéest que les logiques classique, intuitionniste et linéaire apparaissent comme des fragments, c'estádire comme des classes particuliéres de formules et de séquents. Par exemple la démonstration d'unénoncéintuitionniste pourra utiliser des lemmes classiques ou intuitionnistes sans limitation: simplement aprèsélimination des coupures, la démonstration se fera entièrement dans le fragment intuitionniste, ce qui est superficiellement assurépar la propriétéde la sous-formule (seulement des formules intuitionnistes sont utilisées) et plus profondément par un traitement très rigoureux des règles structurelles. Cette approche est radicalement différente de l'approche habituelle qui consiste tout bonnementàchanger la règle du jeu quand on veut changer de logique, c'estàdire de style de séquent: ici il n'y a plus qu'une seule logique, qui au grédes utilisation peut apparaître classique, intuitionniste ou linéaire

The Effects of IFRS on Financial Ratios: Early Evidence in Canada

This paper provides preliminary evidence of the impact on financial ratios caused by the transition to International Financial Reporting Standards (IFRS) in Canada. The main features of IFRS are explained in the context of a shift from Canadian Generally Accepted Accounting Principles (GAAP) while the main differences between the two sets of rules are underscored – heavier reliance of IFRS on fair value accounting and comprehensive income, and the use of the entity theory for consolidation. The effects of IFRS on financial ratios in the areas of liquidity, leverage, coverage and profitability are discussed and verified using a sample cohort of early adopters in Canada. The preliminary evidence reveals significantly higher volatility to most of the ratios under IFRS when compared to those derived under pre-changeover Canadian GAAP. While the means and medians of IFRS ratios differ from the means and medians of the same ratios under pre-changeover Canadian GAAP, the differences are not statistically significant overall. However, important individual discrepancies are in some cases observed. Naturally, analysts using ratios for analytical purposes during the transition period need to be vigilant as ratios computed under IFRS are not directly comparable with those derived under pre-changeover Canadian GAAP. It is recommended that heightened attention be directed to the new feature – comprehensive income – which incorporates unrealized gains and losses that bypass the income statement. The suggested analytical tools best suited to mitigate the contributing effect include reliance on comprehensive-Return on Assets (ROA) and comprehensive-Return on Equity (ROE).IFRS, financial ratios, first application of IFRS

Study of Geographical Variation in Kiln-Drying Behavior of Plantation-Grown White Spruce

White spruce (Picea glauca |Moench| Voss) is one of the most important tree species for reforestation in Canada. Over the past 30 years, hundreds of thousands of hectares were planted. Plantation-grown wood will become an important source of supply for the lumber industry in the near future. Plantation wood is generally known to have a greater proportion of juvenile wood than that from natural stands. For this reason, quality attributes of lumber from plantations might be considerably reduced, especially after kiln-drying. However, these quality attributes might be influenced by the origin of the seed sources used for the reforestation program. The main purpose of this study was to investigate the genetic variation in the effect of kiln-drying under restraint on shrinkage and warp of dimension lumber processed from 26 provenances originating from the Great Lakes and St. Lawrence Region. Two drying treatments were applied, i.e. conventional and high-temperature drying. Analyses of variance showed no significant differences among provenances for any type of shrinkage (longitudinal shrinkage, shrinkage in thickness, shrinkage in width) or warp (bow, crook, twist) measurements. For the effect of the drying treatment, it was significant only in the case of shrinkage in width

On the unity of logic

Projet FORMELRésumé disponible dans le fichier PD

A New constructive logic : classical logic

Projet FORMELRésumé disponible dans le fichier PD

Five Conferences on Undecidability

These five lectures on undecidability were given to students with a good level in mathematics but with no special knowledge on logic. The first conference presents the formalization of mathematics with a short historical survey, the language of first order predicates and the axioms of set theory. The second and third lectures explain the incompleteness phenomena from the Hilbert program until Gödel's theorems with a presentation of the sequent calculus of Gentzen.The fourth talk deepens model theory reasoning in the case of the continuum hypothesis, and the last conference gives examples of effective computability results

A System of Interaction and Structure II: The Need for Deep Inference

This paper studies properties of the logic BV, which is an extension of multiplicative linear logic (MLL) with a self-dual non-commutative operator. BV is presented in the calculus of structures, a proof theoretic formalism that supports deep inference, in which inference rules can be applied anywhere inside logical expressions. The use of deep inference results in a simple logical system for MLL extended with the self-dual non-commutative operator, which has been to date not known to be expressible in sequent calculus. In this paper, deep inference is shown to be crucial for the logic BV, that is, any restriction on the ``depth'' of the inference rules of BV would result in a strictly less expressive logical system

Bounded Linear Logic

A typed, modular paradigm for polynomial time computation is proposed

Sublogarithmic uniform Boolean proof nets

Using a proofs-as-programs correspondence, Terui was able to compare two models of parallel computation: Boolean circuits and proof nets for multiplicative linear logic. Mogbil et. al. gave a logspace translation allowing us to compare their computational power as uniform complexity classes. This paper presents a novel translation in AC0 and focuses on a simpler restricted notion of uniform Boolean proof nets. We can then encode constant-depth circuits and compare complexity classes below logspace, which were out of reach with the previous translations.Comment: In Proceedings DICE 2011, arXiv:1201.034