MIRROREDPOREP: Can we avoid the zigzag technique and replace it by mirroring?

[nicola]

Each node in a graph has chung parents and drg parents. However, the set of edges changes on odd layers, drg parents are simply mirrored, while chung parents are inverted (with a technique described here: https://www.overleaf.com/3456316943pfxsqxkdghsy
).

Can we also simply mirror the DRG parents? if possible, this would allow to have a simplified version on #141 (amortized trees)

[nicola]

old issue, closing