$q$-Analogues of $π$-Related Formulae from Jackson's $_8φ_7$-Series via Inversion Approach (2108.12796v1)

Abstract: By making use of the multiplicate form of the extended Carlitz inverse series relations, we establish two general dual' theorems of Jackson's summation formula for well--poised $_8\phi_7$-series. Their duplicate forms under the partition pattern $n=\lfloor{\frac{n}2}\rfloor+\lfloor{\frac{n+1}2}\rfloor$ are explored and yield numerous $q$-series identities whose limiting cases as $q\to1$ result in classical $\pi$-related Ramanujan--like series of convergence rate$\frac1{16}$" including one for $1/\pi^2$ discovered by Guillera (2003). The triplicate dual formulae under the partition pattern $n=\lfloor{\frac{n}3}\rfloor+\lfloor{\frac{n+1}3}\rfloor+\lfloor{\frac{n+2}3}\rfloor$ are examined via thereverse bisection method", which leads us to twenty new $q$-series identities together with their classical counterparts of convergence rate`$\frac{-1}{27}$" when $q\to1$.