Dynamic constraint and variable aggregation in column generation.

•Improved column-generation decompositions (ICG) are introduced to face degeneracy.•Variables/constraints are aggregated based on algebraic properties of the problem.•Descent directions are computed by an easy to solve (less dense) auxiliary problem.•New theoretical results on the quality of dual solutions are presented.•Reduction factors exceed 10 compared to a state-of-the-art column-generation solver.