text: Very few, trivial, isoglosses exist that separate all Chakavian speeches from all other Western South Slavic dialects nor do exist common isoglosses to all Chakavian sub-dialects from which would be possible a deduction of a "Proto-Chakavian" dialect or language (which is possible with Proto-Kajkavian and Proto-Shtokavian). Ranko Matasović concludes as well that "the Chakavian dialect was never entirely unique, i.e. it is not possible to find common linguistic innovations that would encompass all Chakavian speeches", "while common-Shokavian and common-Kaikavian innovations do exist". There exist significant differences between Northern and all other Chakavian sub-dialects, as Northern Chakavian has characteristics common with Slovene and Kajkavian while Southern Chakavian with Western Shtokavian, but also Northern Chakavian has with Shtokavian, and both Northern and Southern Chakavian have with the Kajkavian dialect. Many linguists, including Aleksandar Belić, Stjepan Ivšić, Zvonimir Junković, Pavle Ivić, Dalibor Brozović among others, in their comparative analysis concluded that Chakavian is closely related to Western Shtokavian (particularly those of Schakavian ikavian expression like the Slavonian dialect and Younger Ikavian dialect). Ivić for example concluded that the Chakavian dialect is genetically much closer to Shtokavian than Kajkavian, and initially argued that "Historically speaking, Chakavian is to a considerable extent a peripheral zone of Shtokavian which (in) many respects lagged behind the development of the [Shtokavian] core, and which parts developed locally limited innovations (with the fact that its Northwestern branches had from the very beginning specific evolutionary contacts with the Slovenian language)". Brozović argued four accentological cores from which dialects emerged, one in which were grouped few Chakavian speeches, while the majority of Chakavian speeches were grouped with Western Shtokavian dialect (Southeastern Chakavian) and part of Southern-Slavonian dialect (Northwestern and Central Chakavian). Today, Chakavian is mostly considered as a separate and unique linguistic system which can be further divided.