My first thought from the title was that this result is in the Blum-Shub-Smale computational model rather than the traditional Turing machine model. In the BSS model, arithmetic operations on exact real numbers are done in constant time. That is useful for analyzing numerical algorithms where you are more interested in e.g. convergence speed than things like roundoff errors. But the exact real arithmetic in constant time is equivalent to doing infinite-precision integer arithmetic in constant time. A couple of people already have mentioned the latter as an assumption of the paper as if that were a big error, but in the BSS model it is part of the deal. Thus the BSS model gives speedups for some problem classes and it's not a big surprise that P=NP there.<p>I didn't realize P vs NP was supposed to be an open problem in the BSS model. I thught that this solution was an early result. The catch is simply that it doesn't apply to the Turing machine model which is what most people think of when they hear of P vs NP.<p>There is a wonderful and mathematically accessible book from the 1990s about the BSS model: Complexity and Real Computation, by Lenore Blum, Felipe Cucker, Michael Shub, and Steve Smale. I thought it was going to open up into a big field, but I don't know if much happened with it.<p>See also: <a href="https://en.wikipedia.org/wiki/Blum%E2%80%93Shub%E2%80%93Smale_machine" rel="nofollow">https://en.wikipedia.org/wiki/Blum%E2%80%93Shub%E2%80%93Smal...</a>