According to the preface the purpose of this NATO Advanced ScienceInstitute ... was to obtain a complete perspective of the field also with aseries of promising... » 

According to the preface the purpose of this NATO Advanced ScienceInstitute ... was to obtain a complete perspective of the field also with aseries of promising directions of research and some recent results. Thispurpose seems to me to have been admirably fulfilled and the organisersspeakers and editor deserve great credit for this anyone seriously interestedin the subject will certainly wish to have this volume available. Metrika 332 1986 «