^Q can be generalized as yet another T, denotade sa ^T (^ hints that it this "live" T may be applied on top of other Ts / maintains a "live" view).
This gives the ability for a ^T to depend on other ^Ts.
So, for each ^T in Ts, ^T(I(Ts)) = ^T(DB).
Additionally, DB is a snapshot. Perhaps ^T(DB) better denoted as ^T(Ts).
Thus the relation can be written as
ΔV = D(^T(Ts)
Additionally, D is akin to Δ, denoting it as such we end up with
ΔV = Δ^T(Ts), for each ^T in Ts.
And since Ts are versioned, ^T(TsN) implicitly has access to ^T(TsN-1).
I.e., TsN contains ^T(TsN-1), for each ^T.
Which allows ^T to be incrementally computed over it's previous value.
^T(^T(TsN-1), TN)
^T has function signature akin to that of reduce, i.e., ^T(accumulator, sequence element)