Simon Špacapan, SEPARATION OF CARTESIAN PRODUCTS OF GRAPHS INTO SEVERAL CONNECTED COMPONENTS BY THE REMOVAL OF EDGES, Applicable Analysis and Discrete Mathematics, Vol. 15, No. 2 (October 2021), pp.

The nsis number 𝒵 (G) is the maximum cardinality of a nonseparating independent set of G. It is well known that computing the nsis number of graphs is NP-hard even when restricted to 4-regular graphs ...