It is argued that the distinction between the normative and the descriptive interpretation of norm sentences can be regarded as a distinction between two kinds of utterances. A norm or a directive has as its content a normative proposition. A normative (performative) utterance of a normative proposition in appropriate circumstances makes the proposition true, and an assertive (descriptive) utte...

Norms have been considered an attractive means for the regulation of the dynamics of multi systems (MAS). Typically, it is left for the individual agents to apply (general) norms to the particular concrete situations that arise during the operation of the system. This paper summarises our work on situated normative infrastructures for multi-agent systems, which aim to facilitate the operational...

The olive (Olea europaea L.) is a typical important perennial crop species for which the genetic determination and even functionality of self-incompatibility (SI) are still largely unresolved. It is still not known whether SI is under gametophytic or sporophytic genetic control, yet fruit production in orchards depends critically on successful ovule fertilization. We studied the genetic determi...

In Podospora anserina, protoplasmic incompatibility (a phenomenon that prevents heterokaryon formation because of the destruction of the fused cells) can be studied in homokaryotic strains that combine nonallelic incompatibility genes or carry mutations at the lys loci. In these strains cell destruction occurs early in development and is associated with an arrest of growth.-From the self-lysing...

In filamentous fungi, a programmed cell death (PCD) reaction occurs when cells of unlike genotype fuse. This reaction is caused by genetic differences at specific loci termed het loci (for heterokaryon incompatibility). Although several het genes have been characterized, the mechanism of this cell death reaction and its relation to PCD in higher eukaryotes remains largely unknown. In Podospora ...

The evolution of distyly from tristyly was investigated in populations of Oxalis alpina at high elevations throughout the Sky Islands of the Sonoran Desert. Incompatibility systems in tristylous populations, where self-incompatible short-, mid-, and long-styled morphs occur in populations, vary from those typical of tristylous species in which each morph is equally capable of fertilizing ovules...