Oh cieca cupidigia, oh ira folie, Che si ci sproni nella vita corta, E
nell' eterna poi si mal c'immolle! o blind greediness and foolish rage,
That in our fleeting life so goads us on And plunges us in boiling blood
for ever! Dante, The Divine Comedy Inferno, XII, 17, 49/51. On an
afternoon hike during the second Oberwolfach conference on Mathematical
Programming in January 1981, two of the authors of this book discussed a
paper by another two of the authors (Korte and Schrader [1981]) on
approximation schemes for optimization problems over independence
systems and matroids. They had noticed that in many proofs the
hereditary property of independence systems and matroids is not needed:
it is not required that every subset of a feasible set is again
feasible. A much weaker property is sufficient, namely that every
feasible set of cardinality k contains (at least) one feasible subset of
cardinality k - 1. We called this property accessibility, and that was
the starting point of our investigations on greedoids.