ϕ23⁡(a,b,cd,e;q,d⁢ea⁢b⁢c)=(e/b,e/c,c⁢q/a,q/d;q)∞(e,c⁢q/d,q/a,e/(b⁢c);q)∞⁢ϕ23⁡(c,d/a,c⁢q/ec⁢q/a,b⁢c⁢q/e;q,b⁢qd)-(q/d,e⁢q/d,b,c,d/a,d⁢e/(b⁢c⁢q),b⁢c⁢q2/(d⁢e);q)∞(d/q,e,b⁢q/d,c⁢q/d,q/a,e/(b⁢c),b⁢c⁢q/e;q)∞⁢ϕ23⁡(a⁢q/d,b⁢q/d,c⁢q/dq2/d,e⁢q/d;q,d⁢ea⁢b⁢c),