Colouring of Mixed Fuzzy Graph and its Application in COVID19

Graph colouring is used in many applications in real-world systems, including traffic light signalling, map colouring, etc. In social networks, some users follow the profiles of some selected popular users. So, these networks can be designed by directed graphs. Some users do not follow the profiles of others, but they are still connected. So, directed edges and undirected edges are very much useful in social networks. In this paper, a new type of fuzzy graph "Mixed Fuzzy Graph" has been introduced. Colouring of such graphs is defined. Along with this, the chromatic number and strong chromatic number are provided, and related properties are investigated. A numerical application of COVID19 affected networks has been presented using the colouring of mixed fuzzy graphs.