Emergency Stopping Condition

[lducas]

Currently, the main stopping condition for all sieve is the saturation condition, which is not an issue for random lattices; yet, over certain lattices such a condition can not be met. It works great most of the time, but it can fail during BKZ for example, when the considered block is already very reduced.

Each sieve has an emergency exit, typically a upper bound on the number of internal iteration. It is not very consistent between each sieve, and is typically some back of the napkin asymptotic with a magic constant to allow some leeway. This is not very robust.

Todo:

• Find a clever and robust emergency stop condition
• Or, at the very least, systematize, unify and document it.