Before revision:  To preserve the G1 connections , neighboring faces of push-pulled faces need to be made movable, but their motions are not known explicitly. Consequently, it becomes challenging to track the geometry-topology inconsistency caused by these movable faces and to attain a robust update for push-pulled solid models.
After revision:  To preserve the G1 connections , it is often desirable to preserve these connections for functional, manufacturing, or aesthetic reasons, but this could cause complex inconsistencies between the geometry and topology in the model and lead to robustness issues in updating the model. The challenge lies in effectiveness towards detecting the instants when geometry-topology inconsistency caused by these movable faces and to attain a robust update for push-pulled solid models.