Mergeable weighted majority games and characterizations of some power indices

In this paper, we introduce a notion of mergeable weighted majority games with the aim of providing the first characterization of the Colomer-Mart\'inez power index (Colomer and Mart\'inez in J Theor Polit 7(1):41-63, 1995). Furthermore, we define and characterize a new power index for the family of weighted majority games that combines ideas of the Public Good (Holler in Polit Stud 30(2):262-271, 1982) and Colomer-Mart\'inez power indices. Finally, we analyze the National Assembly of Ecuador using these and some other well-known power indices.