A family H of sets is said to be hereditary if all subsets of any set in H are in H; in other words, H is hereditary if it is a union of power sets. A family A is said to be intersecting if no two sets in A are disjoint. A star is a family whose sets contain at least one common element. An outstanding open conjecture due to Chvátal claims that among the largest intersecting sub-families of any ...

Twitter has been regarded as an outstanding social media application due to its immediacy in communication. Twitter has experienced exponential growth and been used for various purposes including crisis communication. However, there have been less empirical studies on Twitter messages (tweets) posted during crisis. In this paper, we analyse the tweets that were posted during Australia’s worst f...