This volume is a result of a meeting which took place in June 1986 at
'll Ciocco" in Italy entitled 'Deformation theory of algebras and
structures and applications'. It appears somewhat later than is perhaps
desirable for a volume resulting from a summer school. In return it
contains a good many results which were not yet available at the time of
the meeting. In particular it is now abundantly clear that the
Deformation theory of algebras is indeed central to the whole philosophy
of deformations/perturbations/stability. This is one of the main results
of the 254 page paper below (practically a book in itself) by
Gerstenhaber and Shack entitled "Algebraic cohomology and defor- mation
theory". Two of the main philosphical-methodological pillars on which
deformation theory rests are the fol- lowing - (Pure) To study a highly
complicated object, it is fruitful to study the ways in which it can
arise as a limit of a family of simpler objects: "the unraveling of
complicated structures" . - (Applied) If a mathematical model is to be
applied to the real world there will usually be such things as
coefficients which are imperfectly known. Thus it is important to know
how the behaviour of a model changes as it is perturbed (deformed).