I am reducing to 2XSAT, which is a name for instances that are intersections of 2-SAT and XORSAT instances.
Both 2-SAT and XORSAT have polynomial algorithms, why is it hard to believe that their intersection has one too?
There are other ways to improve the method, which (if indeed P=NP) are incredibly interesting - you can directly compose presolved general instances and specialize on them. Kinda like if you need to compute many solutions to linear equations, you only need to factor the matrix once.
I think testing O(n^8) algorithm is pointless, so it needs more polishing (naive algorithm for 2-SAT (that follows from Krom) is O(n^3) or so, but the best methods are linear; so I feel there is a lot of room for improvement, but obviously my method is a little bit more complicated than 2-SAT, which it generalizes).
> I am reducing to 2XSAT, which is a name for instances that are intersections of 2-SAT and XORSAT instances.
It seems to me that 2-SAT and XORSAT are distinct problems. I mean there is no problem instance that is simultaneously a 2-SAT problem and an XORSAT problem instance. So how can there be instances that are intersections of both ?
There are in fact problems that are both 2-SAT and XORSAT, but they seem to be rather trivial - those are linear equations that have up to 2 variables per equation. But that's not what I am talking about.
I understand why people are confused with my off-hand comments, but I didn't plan to explain my approach here in detail, and I typed the first couple of comments when I was at work on my phone, where being precise is tedious.
Yes, 2XSAT is the name I gave it, and I couldn't find it anywhere. The reduction is surprisingly simple, yet nobody mentions it. That's why I am warning people here - just based on this alone, I 80% believe that P=NP with a practical algorithm (which either way involves solving linear equations). And I wouldn't be surprised somebody coming up with the algorithm.
The reason why I say it's an intersection is because that's how the set of solutions of an instance looks like. That's what we need to figure out - how to characterize the sets of solutions described by SAT instance (i.e. sets of assignments to boolean variables that satisfy the instance).
However, it's not that easy, even if you characterize them as interesections of 2-SAT and XORSAT instances, set of solutions to 2-SAT is notoriously hard to characterize too, for example, #2SAT is not known. And polynomial algorithms for 2-SAT and XORSAT are doing very different things, and it's not at all obvious how to generalize them into a common algorithm that can do both.
As a grad student, I got perhaps hundreds of "dear professor" emails claiming proof of everything from squaring the circle to the BSD conjecture. Reflexively running from anybody making such claims is a necessary survival skill. Math is a field where the bullshit asymmetry principle[1] is particularly stark. Finding a flaw in a proof can take vastly more effort than is spent concocting it.
I think professionals of every field have to deal with passionate amateurs of all levels. I understand why many people don't want to do it, but IMHO overemphasis on professionalism (culturally coming from enormous peer pressures) is hurting any field. The superprizes make it even worse.
> Just don't act confident that you've cracked a keystone problem in the field.
I am not acting like that, but I also have to be honest that my goal is specific - to understand why we can or can't have a polynomial algorithm. I.e. I have a strategy already, what I need is a 2nd opinion about some specifics of it.
This is the entire question of P vs NP. I'd love to point you to a reference, but the question remains unresolved. Good hunting.