Mutual visibility

Shukla, Maiti, Kumar and Bhagat add a movement budget: each robot may travel a total distance of at most \(B\), so robots cannot be sent to the corners of a distant convex hull. Their algorithm moves robots by small steps, at most a fixed fraction of the distances to the other robots it sees and to the lines through them, in four phases encoded by the light colours (Section 3): every non-faulty robot first makes one step off the lines through it, the robots at the ends of each line before those between them; then robots that are still between two others step towards the reference point, the farthest from it first, which breaks cyclic dependencies; finally robots at the ends of lines make one step towards it, to get past faulty robots. Their goal is stronger than that of Poudel et al. 2021: a non-faulty robot must also see every faulty robot. As reported by Shukla et al. 2026a (Section 1.1 and Table 1), Pramanick, Jana and Mandal solve mobility-fault-tolerant mutual visibility without axis agreement and without a reference point: for one fault in SSYNC and ASYNC and any number in FSYNC (TCS 2025), and for any number of faults in ASYNC with 35 colours in \(O(n)\) epochs (SIROCCO 2026); neither paper is in the bibliography and neither was read. An algorithm for ASYNC would carry over to this setting. Checked against the full text of Shukla et al. 2026a (arXiv v1: model in Section 2, Theorem 1, Lemmas 10 and 21–23) and Section 7 of Di Luna et al. 2017.