Prove in Zero Knowledge the execution of a function Given a function:

$$Y = a * b$$

Is there a way to prove in zero knowledge that a value $Y$ was gotten, without revealing $a$ and $b$?  Alternatively, that we have knowledge of $a$ and $b$ such that their product equals $Y$.

public : $Y$

private: $a$,$b$
Yes, what you describe is an example of a zero-knowledge proof.

ZKP systems such as libSNARK, libSTARK, pepper-project, etc. can help the prover generate a proof that he/she knows private $a$ and $b$ such that $Y = a * b$ and then a verifier can check that the computation was done correctly without ever knowing $a$ and $b$.

What you describe is the knowledge-of-factorization example and I recently implemented that in the pepper-project here.