It is well known now that Yitang Zhang's work on Jacobian conjecture collapsed because his advisor's work earlier contains unjustified claims. I am wondering what specifically is unclear about [his paper](https://eudml.org/doc/152524). From fellow researchers I heard his paper is unreadable, and the last claim in his paper on Jacobi conjecture may even be wrong (among other things, he claim that there are *no counter examples of degree less than 100*). Later, [a paper by his student](https://arxiv.org/abs/1604.07683) appeared which claimed to have repaired the gap. Unfortunately, it has been suggested to me both papers are unreadable. 


While Yitang Zhang suggested in an interview that Moh's paper is "neither correct nor incorrect", Moh claim that the paper is [indeed correct](https://www.math.purdue.edu/~ttm/ZhangYt.pdf) (page 8) without giving any explanation on the main idea of his paper. Yitang Zhang's opinion may be quoted at [here](https://books.google.com/books?id=HAdrAwAAQBAJ&pg=PT93&lpg=PT93&dq=%E4%BB%96%E8%AE%A4%E4%B8%BA%E4%BB%96%E6%98%AF%E5%AF%B9%E7%9A%84%EF%BC%8C%E8%80%8C%E4%B8%94%E8%B0%81%E9%83%BD%E7%9B%B8%E4%BF%A1%E4%BB%96%E6%98%AF%E5%AF%B9%E7%9A%84%EF%BC%8C%E4%BD%86%E6%98%AF%EF%BC%8C%E4%BB%96%E6%B2%A1%E6%9C%89%E8%AF%81%E5%87%BA%E6%9D%A5%20%E5%90%8D%E6%98%9F&source=bl&ots=TcxcMTT2Up&sig=b1l7WLqfSmvoYj1govaV5RfJhHU&hl=en&sa=X&ved=2ahUKEwjK5q7Pj_LdAhVIhq0KHZecDIgQ6AEwAHoECAkQAQ#v=onepage&q=%E4%BB%96%E8%AE%A4%E4%B8%BA%E4%BB%96%E6%98%AF%E5%AF%B9%E7%9A%84%EF%BC%8C%E8%80%8C%E4%B8%94%E8%B0%81%E9%83%BD%E7%9B%B8%E4%BF%A1%E4%BB%96%E6%98%AF%E5%AF%B9%E7%9A%84%EF%BC%8C%E4%BD%86%E6%98%AF%EF%BC%8C%E4%BB%96%E6%B2%A1%E6%9C%89%E8%AF%81%E5%87%BA%E6%9D%A5%20%E5%90%8D%E6%98%9F&f=false):



> 
> 张益唐：他认为他是对的，而且谁都相信他是对的，但是，他没有证出来。他告诉我他的研究是对的，我照着他说的路子就都做出来了，但回过头来才发现，没有证据证明他是对的。我也不认为他是错的，但他还没有拿出证据证明他是对的。
> 
> 
> 


The passage may be translated as:



> 
> Yitang Zhang: He believed he was correct, and everyone believed he was
>  correct. But he did not prove the result he claimed. He told me his
>  research is correct, and I proved (Jacobi conjecture?) by what he
>  suggested. However, when I reckon the proof, **I discovered there is
>  no evidence suggesting he is correct**. I also do not believe he is
>  wrong; but he has not provided evidence to show it is correct.
> 
> 
> 


What is the current consensus? I ask this because a colleague in my department got seriously stumped on the paper. If the paper is correct and there is no gap in the paper, I imagine Prof. Zhang or anyone else in his situation would be eager to publish the result. So I am genuinely confused. 


Q1: Does Moh's paper really contain a gap? 


Q2: If Moh's paper is complete and correct as he claimed, is there any follow up work explaining the numerical reason behind the $(99,66)$ degree case? 



Does T-T Moh's paper really contain a gap?
Yes, there appears to be a follow-up work by Yansong Xu on the (99,66)-case: [Intersection Numbers and the Jacobian Conjecture](https://arxiv.org/abs/1604.07683v2), in turn followed by [The Jacobian Conjecture: Approximate roots and intersection numbers](https://arxiv.org/abs/1708.09367) by Guccione-Guccione-Horruitiner-Valqui. As their abstract says, they have obtained "nearly the same formulas for the intersection number of Jacobian pairs (as Xu), but with an inequality instead of an equality".


