The April 2021 issue of Networks addresses both theoretical and algorithmic advances for a variety of deterministic and stochastic network optimization problems. The specific contributions detailed in this issue are
• application of interval graphs to the scheduling of jobs using in-house and third-party machines,
• complexity analysis and algorithms for protecting vertices in a graph from the spread of infection,
• efficient algorithms for finding 2-medians in a tree graph,
• efficient algorithms for computing the diameter and radius of Helly graphs, which generalize interval graphs,
• parameter estimation in a random graph model using mean-field approximation,
• polynomial-time algorithms for time-dependent shortest path problems,
• analysis of online secretary problems in which candidates can return.
We trust that the readership of INFORMS will find these articles to be of interest.
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Douglas Shier
Bruce Golden
Editors-in-Chief, Networks
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