Minimal Paradefinite Logics for Reasoning with Incompleteness and Inconsistency

Paradefinite (`beyond the definite\u27) logics are logics that can be used for handling contradictory or partial information. As such, paradefinite logics should be both paraconsistent and paracomplete. In this paper we consider the simplest semantic framework for defining paradefinite logics, consisting of four-valued matrices, and study the better accepted logics that are induced by these matrices

Safety, Absoluteness, and Computability

The semantic notion of dependent safety is a common generalization of the notion of absoluteness used in set theory and the notion of domain independence used in database theory for characterizing safe queries. This notion has been used in previous works to provide a unified theory of constructions and operations as they are used in different branches of mathematics and computer science, including set theory, computability theory, and database theory. In this paper we provide a complete syntactic characterization of general first-order dependent safety. We also show that this syntactic safety relation can be used for characterizing the set of strictly decidable relations on the natural numbers, as well as for characterizing rudimentary set theory and absoluteness of formulas within it

What is a Paraconsistent Logic?

Paraconsistent logics are logical systems that reject the classical principle, usually dubbed Explosion, that a contradiction implies everything. However, the received view about paraconsistency focuses only the inferential version of Explosion, which is concerned with formulae, thereby overlooking other possible accounts. In this paper, we propose to focus, additionally, on a meta-inferential version of Explosion, i.e. which is concerned with inferences or sequents. In doing so, we will offer a new characterization of paraconsistency by means of which a logic is paraconsistent if it invalidates either the inferential or the meta-inferential notion of Explosion. We show the non-triviality of this criterion by discussing a number of logics. On the one hand, logics which validate and invalidate both versions of Explosion, such as classical logic and Asenjo–Priest’s 3-valued logic LP. On the other hand, logics which validate one version of Explosion but not the other, such as the substructural logics TS and ST, introduced by Malinowski and Cobreros, Egré, Ripley and van Rooij, which are obtained via Malinowski’s and Frankowski’s q- and p-matrices, respectively

Heparin inhibition of ferredoxin-NADP reductase in chloroplast thylakoid membranes

Heparin, an anionic polysaccharide, inhibited the ferredoxin-catalyzed reduction of NADP in spinach chloroplast thylakoid membranes. Under the same conditions of assay, heparin did not interfere markedly with photoreduction of methyl viologen, anthraquinone sulfonate, or ferredoxin. A kinetic analysis of the heparin-induced interference with NADP photoreduction showed partial competitive inhibition. Heparin also interfered with NADPH oxidation by membrane-bound ferredoxin-NADP reductase (with dichlorophenol-indophenol as the acceptor) by a mechanism that involves partial competitive inhibition. This reaction was sensitive to the presence of salts; increasing ionic strength increases the heparin Ki for inhibition of NADPH oxidation. These results show that heparin binds to ferredoxin-NADP reductase, and in doing so interferes with binding to the reductase by both ferredoxin and NADP(H). Since heparin is redox inactive and does not interfere with the photophosphorylation reaction, it is a useful inhibitor of thylakoid membrane reactions which require the catalytic activity of ferredoxin-NADP reductase.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/25772/1/0000333.pd

Properties of the cyanobacterial coupling factor ATPase from Spirulina platensis : I. Electrophoretic characterization and reconstitution of photophosphorylation

The coupling factor ATPase (F1) from photosynthetic membranes of the cyanobacterium Spirulina platensis was purified to homogeneity by a combination of ion-exchange chromatography and sucrose density gradient centrifugation. The ATPase activity of purified Spirulina F1 is latent but can be elicited by trypsin treatment, resulting in specific activities (CaATPase) of 27-37 [mu]mol Pi min-1 mg protein-1. On denaturing sodium dodecyl sulfate-polyacrylamide gradient gels, Spirulina F1 is resolved into five subunits with molecular weights of 53,400, 51,600, 36,000, 21,100, and 14,700, similar to the molecular weights of the subunits of spinach chloroplast coupling factor (CF1). As determined by native polyacrylamide gradient gel electrophoresis, the molecular weight of the Spirulina F1 holoenzyme was estimated to be 320,000, somewhat smaller than the estimated molecular weight of spinach CF1 (392,000). Spirulina F1 was shown to be an active coupling factor by its ability to reconstitute phenazine methosulfate-dependent cyclic photophosphorylation in membrane vesicles which had been depleted of coupling factor content by 2 NaBr treatment. We estimate the Spirulina F1 content of membrane vesicles to be 1 F1 per 830 chlorophylls or 0.12 mol F1 mol P700-1, based on the specific ATPase activities of the membrane vesicles and the purified Spirulina F1, the molecular weight of F1, and the P700 content of the vesicles.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/26257/1/0000338.pd