In the vernacular of the Roussish dialects which more or less widely use the fully conjugated verb 'bouti' only (but ye and sõty) the so called apheretic forms are attested. Based on this, the standard or received pronunciation of these forms is to be the following:
yesmi [sjmɪ]
yesi [jsɪ, jsɪ, ɩsɪ]
yesmo [sjmɔ, sjmɒ]
yeste [sjtɛ, sjtɜ].
Previously, I considered to make regular several orthographies for these forms: the fully written forms for fully pronounced ones, and the apostrophized orthography for the syncopic ones (i.e. y'si for yesi, y'ste for yeste). Later on I noticed, that this shares in common with the word [ʃʧɛ ~ ʃʧɜ] 'more. also. still; yet', for which - despite various conjectures on its initial form in Old West Roussish (*osce, *yesce, even *isce) - I choose to write yesce with the standardized pronunciation [ʃʧɛ ~ ʃʧɜ ~ ʃʧe]. On these grounds, as a fact of mutual indirect proof, I deal, that syncopation in the bouti conjugated personal forms and in the word yesce is, though widespread and standardized, is not a result of any historical morphological mutation, but a matter of prosody or phonotactics.
The forms yesmi, yesi, besides apheretic normal pronunciation have also an apocopic variant of pronunciation, i.e. [jem], [jesj], and even fully syncopized, i.e. with both apheresis and apocope, like [m], [sj]. So, the phrase like: 'Boula yesi fycyora doma?' can be pronounced as: [bulɑsjuʧɒrɑdɒmɑ?], and the phrase like: 'Boul yesi fycyora doma' can be pronounced as: [buwesjuʧɒrɑdɒmɑ?].
The fully pronounced forms (i.e. [jesmɪ], [jesɪ], [jesmɔ], [jestɛ]) I mean to revive for the sake of formal status, and in terms of prosody for an emphatisized retort. Premised on the prescriptive nature of this grammar I see a good perspective for the use of the fully pronounced forms in predicative sentences of statement. That is, take a question 'Yeste tam?' [sj`tɛtɑm] - in case of a simple positive answer it would suffice to formulate it merely 'Yesmo' [jɛ`smɔ], yet syncopic form [sjmɔ] is normal here as well.
Interestingly, the standard modern Roussish (Ucrainian) doesn't enjoy this advantageous manoeuvre. Now, let's take again the above question 'Ci fui tam?' (purposely without verb 'bouti') and the positive answer as it would sound upon the modern standard - 'Mui tout'. See, an average Ucrainian would barely notice the oddity this question-answer pair instills: from the viewpoint of the other Slavic languages which standardly use the conjugated 'be'-verb, and the neighbouring Hungarian language likewise, the in such a manner stated question and answer will be interpreted as follows: 'Are you there?' - (No,) we are there (the underlining here means emphasis), which looks totally confusing, much less the redundance of such a phrasing in the modern standard.
