Armenian is an independent branch of the Indo-European languages. It is of interest to linguists for its distinctive phonological developments within that family. Armenian exhibits more satemization than centumization, although it is not classified as belonging to either of these subgroups. Some linguists tentatively conclude that Armenian, Greek (and Phrygian) and Indo-Iranian were dialectally close to each other; within this hypothetical dialect group, Proto-Armenian was situated between Proto-Greek (centum subgroup) and Proto-Indo-Iranian (satem subgroup). Ronald I. Kim has noted unique morphological developments connecting Armenian to Balto-Slavic languages.