23 mai 2022Florent Capelli (INRIA Lille équipe LINKS)
Enumeration algorithms are algorithms whose goal is to
output the set of all solutions to a given problem. There exists
different measures for the quality of such algorithm, whose relevance
depends on what the user wants to do with the solutions set.
If the goal of the user is to explore a subset of solutions or to
transform the solutions as they are outputted with a stream-like
algorithm, a relevant measure of the complexity in this case is the
delay, that is, the maximal time between the output of two distinct
solutions. Following this line of thoughts, significant efforts have
been made by the community to design polynomial delay algorithms, that
is, algorithms whose delay between the output of two new solutions is
polynomial in the size of the input.
While this measure is interesting, it is not always completely
necessary to have a bound on the delay and it is enough to ask for a
guarantee that running the algorithm for O(t poly(n)) will produce at
least t solutions. While algorithms having this property can be
transformed into polynomial delay algorithm, the naive transformation
may result in a blow up in the space used by the enumerator.
In this talk, we will present a new technique that allow to transform
such algorithms into polynomial delay algorithm with only a polynomial
overhead on the space.