0
$\begingroup$

During my research on extension of the Jacobi Triple Product. , I finally got an interesting conjecture that is similar and extension of of the Jacobi Triple Product for higher terms . I asked a related question 3 years ago. (The link of my question is) . It should be true with strong sense. I need help to disprove or prove my conjecture (1) below. I do not know if it is known theorem or not.

$$[\phi(qh)-\phi(qh^{-1})]\prod\limits_{n=1}^{ \infty }(1-q^{n}h^{n^2})(1-q^{n}h^{-n^2})=\sum\limits_{n = - \infty }^ \infty (-1)^n q^{\frac{n(n+1)}{2}} h^{\frac{n(n+1)(2n+1)}{6}} \tag 1 $$

Where $\phi(q)$ is Euler function and $h=e^{i.x}$ , $x$ is Real Number

$$\phi(q)=\prod\limits_{n=1}^{ \infty }(1-q^{n})=\sum\limits_{n = - \infty }^ \infty (-1)^n q^{\frac{n(3n-1)}{2}} \tag 2$$

if the series are extended in positive powers of $q$ with coefficients that are Laurent polynomials in $h$, I confirmed the Equation (1) for first few terms (I have confirmed $q^3$ terms manually for now) . I do not have math software extend such q series with $h$ variables in it .

Could you please help me to confirm more terms if my conjecture is true for more terms? I will be very appreciated for confirmation for higher terms or disprove for higher terms that the conjecture is false for higher terms.

$$\phi(qh)-\phi(qh^{-1})= q(h^{-1}-h)+q^2(h^{-2}-h^{2})-q^5(h^{-5}-h^{5})+.... \tag 3 $$

$$\prod\limits_{n=1}^{ \infty }(1-q^{n}h^{n^2})(1-q^{n}h^{-n^2})=1-q(h^{-1}+h)+q^2(1-h^{-4}-h^4)+q^3(h^3+h^{-3}+h^5+h^{-5}-h^9-h^{-9})+....\tag 4$$

$$[\phi(qh)-\phi(qh^{-1})]\prod\limits_{n=1}^{ \infty }(1-q^{n}h^{n^2})(1-q^{n}h^{-n^2})=q(h^{-1}-h)-q^3(h^{-5}-h^5)+.... \tag 5$$

$$\sum\limits_{n = - \infty }^ \infty (-1)^n q^{\frac{n(n+1)}{2}} h^{\frac{n(n+1)(2n+1)}{6}}=q(h^{-1}-h)-q^3(h^{-5}-h^5)+.....\tag 6$$

Thanks a lot for helps

$\endgroup$
3
  • $\begingroup$ When $h=1$, the LHS is zero but the RHS is not. Did you miss a "$+1$" on the LHS? My suspicion is that generalizing Jacobi is unlikely. $\endgroup$ Dec 28, 2016 at 16:29
  • $\begingroup$ @T.Amdeberhan When $h=1$ , $\sum\limits_{n = - \infty }^ \infty (-1)^n q^{\frac{n(n+1)}{2}}=0$. It is not problem. $\endgroup$
    – Mathlover
    Dec 28, 2016 at 16:35
  • $\begingroup$ Oh, you're right. $\endgroup$ Dec 28, 2016 at 16:45

1 Answer 1

2
$\begingroup$

Your conjecture is false. The coefficient of $q^{4}$ in the left hand side is $$ -h^{-10} + h^{-8} + h^{-2} - h^{2} - h^{8} + h^{10} $$ (and not zero, like you had conjectured).

$\endgroup$
1
  • 1
    $\begingroup$ Thanks for answer. I will double check my all notes again . I will update my conjecture. $\endgroup$
    – Mathlover
    Dec 28, 2016 at 16:37

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.