Blaschke’s “More down than up” conjecture for generalized hypergeometric series
Prove Blaschke’s conjecture asserting that for the generalized hypergeometric function pFq in which k numerator parameters and m denominator parameters are shifted by ±a, if k < m, then as |a| → ∞ the defining Taylor series in z is an asymptotic expansion for some values of z, with the asymptotic form given by the ratio of Pochhammer products for the shifted parameters.
References
Please note Blaschke's conjecture [6, p. 1791]: Regardless of the sign, when more large parameters are down than up, the resulting Taylor series defining F(a, z) is always an asymptotic expansion for some values of z. That is, if k < m, then F (a, z) ~ ∞ (a)±a)n·(ak±a)n(ak+1)n·(ap)nz" |a|-8. n=0 (b]±a)n ... (bm ±a)n (bm+1)n ... (bg)n n!'
— Asymptotics of the Humbert functions $Ψ_1$ and $Ψ_2$
(2501.07281 - Hang et al., 13 Jan 2025) in Section 7, Concluding remarks