Is 'That is to say, beside Indo-European and Indo-Hittite, there must have existed an Indo-Slurvian.' an autonomous statement, not logically connected to 'There must definitely not exist an Indo-Slurvian.'
That is to say, beside Indo-European and Indo-Hittite, there must have existed an Indo-Slurvian.###There must definitely not exist an Indo-Slurvian.