In 1985 the traditional Arbeitstagimg at Bonn was cancelled. Instead a number of
workshops were organized during Spring and Summer 1985 by various organizers.
One of these workshops was on number theory with special emphasis on diophantine
problems and transcendence. It took place at the Max-Planck-Institut fur Mathematik
at Bonn in May - June 1985. A great number of leading mathematicians in the subject
were invited for a certain period to discuss mathematics and problems. It seems that a
very fruitful atmosphere was created which is reflected by quite a number of joint
papers which were written during this time at Bonn or at least initiated there.
We are very happy to present in this volume a selection of papers that grew out of this
workshop at Bonn. It consists entirely of research papers which cover various
important aspects of the field and each of them presents a fundamental contribution to
the subject.
In the first contribution by Colliot-Thelene, Kanevsky and Sansuc an effective
algorithm for the calculation of the Manin obstruction for the Hasse principle for
diagonal cubic surfaces is given.
Then in the next article by Masser on small values of heights on families of abelian
varieties, an effective lower bound for the variation of the Neron-Tate height in
families of abelian varieties is given.