New counter-subject: False
Old counter-subject shifted: False
Old counter-subject transposed: False
New combination: False
Remarks: There are two ways to interpret this relationship. The first one is to consider that Sohier has amplified the first Fg in order to make his first Kyrie. The second one is to consider he has seen 'Vidi speciosam'and 'cuius inaestimabilis'as one and the same Fg, broken by another soggetto ('de super rivos aquarum') that he has decided to omit in his missa.
Melodic interval of entry: 4-5-4-4+8+
Time interval of entry: M6/10/6/11/3
Dovetail voice: Superius
Remarks: A very free fuga based on an idea asserted in another comment. I have indicated a CAD that is not really a CAD, as to compare with the mass. This whole song, anyway, counts a lot of cadential clausules for very few CAD actually audible, due to a lot of dovetails and a 'restless'behaviour. The CAD I selected is inverted, I cannot indicate it... As the soggetto of 'Vidi speciosam'is used again on 'Cuius inastimabilis', I have selected the latter, though I do not describe it. (after reflection, I find the actual CAD on bar 28, it could be the model of the CAD in the mass. I will indicate it in another comment)
Melodic interval of entry: 4-5-4-4+5+8-5+8-5-4+5+8-4+
Time interval of entry: M6/6/6/9/2/4/4/10/5/7/2/4/4
Dovetail voice: [Superius]
Remarks: The fuga is based on an ID I have already asserted in another comment. It is hard to find any other structural element in this fuga, as it is quite free. The first kyrie is based on only one element, leading to the CAD.