Topics in the General Theory of Structures

This volume is about "e;Structure"e;. The search for "e;structure"e;, always the pursuit of sciences within their specific areas and perspectives, is witnessing these days a dra- matic revolution. The coexistence and interaction of so many structures (atoms, hu- mans, cosmos and all that there is in between) would be unconceivable according to many experts, if there were not, behind it all, some gen- eral organizational principle. s that (at least in some asymptotic way) make possible so many equilibria among species and natural objects, fan- tastically tuned to an extremely high degree of precision. The evidence accumulates to an increasingly impressive degree; a concrete example comes from physics, whose constant aim always was and is that of searching for "e;ultimate laws"e;, out of which everything should follow, from quarks to the cosmos. Our notions and philosophy have un- dergone major revolutions, whenever the "e;unthinkable"e; has been changed by its wonderful endeavours into "e;fact"e;. Well, it is just from physics that evidence comes: even if the "e;ultimate"e; could be reached, it would not in any way be a terminal point. When "e;complexity"e; comes into the game, entirely new notions have to be invented; they all have to do with "e;structure"e;, though this time in a much wider sense than would have been understood a decade or so ago.