A semi-transparent selective undo algorithm for multi-user collaborative editors

Abstract

Multi-user collaborative editors are useful computer-aided tools to support human-to-human collaboration. For multi-user collaborative editors, selective undo is an essential utility enabling users to undo any editing operations at any time. Collaborative editors usually adopt operational transformation (OT) to address concurrency and consistency issues. However, it is still a great challenge to design an efficient and correct OT algorithm capable of handling both normal do operations and user-initiated undo operations because these two kinds of operations can interfere with each other in various forms. In this paper, we propose a semi-transparent selective undo algorithm that handles both do and undo in a unified framework, which separates the processing part of do operations from the processing part of undo operations. Formal proofs are provided to prove the proposed algorithm under the well-established criteria. Theoretical analysis and experimental evaluation are conducted to show that the proposed algorithm outperforms the prior OT-based selective undo algorithms.

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“…In recent years, the active contour model has been capable of providing closed contours of target objects and has been extensively applied to image segmentation and based on the theory of curve evolution and fluid mechanics [6][7][8][9][10][11]. In the active contour model, the level set method proposed by Osher and Sethian, provides a very effective framework for the numerical description of low-dimensional curves and high-dimensional surfaces [12], and is widely used in image processing and computer vision [13][14][15][16].…”

Untitled

“…In recent years, the active contour model has been capable of providing closed contours of target objects and has been extensively applied to image segmentation and based on the theory of curve evolution and fluid mechanics [6][7][8][9][10][11]. In the active contour model, the level set method proposed by Osher and Sethian, provides a very effective framework for the numerical description of low-dimensional curves and high-dimensional surfaces [12], and is widely used in image processing and computer vision [13][14][15][16].…”

Untitled

“…In recent years, the active contour model has been capable of providing closed contours of target objects and has been extensively applied to image segmentation and based on the theory of curve evolution and fluid mechanics [6][7][8][9][10][11]. In the active contour model, the level set method proposed by Osher and Sethian, provides a very effective framework for the numerical description of low-dimensional curves and high-dimensional surfaces [12], and is widely used in image processing and computer vision [13][14][15][16].…”