Hello,
Sorry, I am new to this and it does look rather messy!
in the first equation it is not dv/dr but dv/d(tau).
All the v's in the equation are the same as the v=α_{1}(τ)ε + α_{0}(τ) which we are seeking a solution for and then V(S, I, t) = e−DτSv(ε, τ).
Incase it is also not...