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To fix notation and check that my definitions are correct I will first state:

abc conjecture: Let $a,b\in\mathbb{N}$ be coprime, $c:=a+b$ , and define the quality of the triple $(a,b,c)$ to equal $q(a,b,c):=\log(c)/\log(\text{rad}(abc))$. Then for each $\varepsilon>0$, the number of such $(a,b,c)$ with $q>1+\varepsilon$ is finite.

However, looking at this table on Wikipedia of qualities of triples with $c<10^{18}$, it would seem possible that for $q\in[1,3/2]$ we have that the number $N(q,n)$ of triples with quality $>q$ and $c<n$ satisfies $N(q,n)=\Omega_q(\log n)$.

This would contradict the abc conjecture, so is there a reason that this behaviour should eventually stop for large $c$? Are there any other reasons (aside from its consequences) to believe that it is true?

My understanding of the conjecture is very superficial - I understand (from Silverman's Arithmetic of elliptic curves, section VIII) that abc implies Szpiro's conjecture, and conversely Szpiro's conjecture implies abc with the 1 replaced with 3/2, but this is the extent of my knowledge. I would also be interested in reasons why one might believe Szpiro's conjecture, which I currently do not have any intuition about.

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    The analog to abc for polynomials is a theorem. https://en.wikipedia.org/wiki/Mason%E2%80%93Stothers_theorem – Gerry Myerson Apr 28 '21 at 13:47
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    The abc conjecture is equivalent to a modified version of the Szpiro conjecture. But I think it's more that it appears to provide a grand synthesis of many of the outstanding conjectures in Diophantine Arithmetic. That, of course, is not evidence for the conjecture, but it is certianly ample justification for its study. If it is false, the counterexamples can be expected to be of considerable interest. – lulu Apr 28 '21 at 13:53
  • Thanks for your comments. Is there a particular reason why the function field analogy should be expected to carry over in this case? For other things involving elliptic curves, such as the unboundedness of ranks over function fields, I've heard skepticism about whether this should still hold. Is there a heuristic why these situations should be different? – user761852 Apr 28 '21 at 13:54
  • Sorry, that's above my pay grade. – Gerry Myerson Apr 29 '21 at 02:42

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