Comparing Wiener, Szeged and revised Szeged index on cactus graphs

We show that on cactus graphs the Szeged index is bounded above by twice Wiener index. For revised situation reversed if graph class further restricted. Namely, all blocks of a are cycles, then its below Additionally, we these bounds sharp and examine cases equality. Along way, provide formulation as sum over vertices, which proves very helpful, may be interesting in other contexts.