The preface and all the papers are available from http://www.programmazionelogica.it/1997/06/xii-iv-appia-gulp-prode-1997-opacgrado-italy/
The preface and all the papers are available from http://www.programmazionelogica.it/1997/06/xii-iv-appia-gulp-prode-1997-opacgrado-italy/