But problem with all of them is that they all are probabilistic in nature. So, here comes one another method i. Features of AKS primality test : 1. The AKS algorithm can be used to verify the primality of any general number given. The maximum running time of the algorithm can be expressed as a polynomial over the number of digits in the target number. The algorithm is guaranteed to distinguish deterministically whether the target number is prime or composite.

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It only takes a minute to sign up. I am trying to get an idea of how the AKS primality test should be interpreted as I learn about it, e. The test has polynomial runtime but with high degree and possible high constants.

I am interested in functionally comparable algorithms, that is deterministic ones that do not need conjectures for correctness. Additionally, is using such a test over the others practical given the test's memory requirements?

First, let's separate out "practical" compositeness testing from primality proofs. The former is good enough for almost all purposes, though there are different levels of testing people feel is adequate.

This will be vastly faster than AKS and be just as correct in all cases. Almost all of the proof methods will start out or they should with a test like this because it is cheap and means we only do the hard work on numbers which are almost certainly prime. Moving on to proofs. In each case the resulting proof requires no conjectures, so these may be functionally compared. These use binary segmentation in GMP for the polynomial multiplies so are pretty efficient, and memory use is a non-issue for the sizes considered here.

But extrapolating out to digits arrives at estimated times in the hundreds of thousands to millions of years, vs. There are further optimizations which could be done from the Bernstein paper, but I don't think this will materially change the situation though until implemented this isn't proven.

Eventually AKS beats trial division. The BLS75 theorem 5 e. This works great at small sizes, and also when we're lucky and n-1 is easy to factor, but eventually we'll get stuck having to factor some large semi-prime. There are more efficient implementations, but it really doesn't scale past digits regardless. We can see that AKS will pass this method. So if you asked the question in and had the AKS algorithm back then we could calculate the crossover for where AKS was the most practical algorithm.

Primo free but not open source ECPP will be faster for larger digit sizes and I'm sure has a nicer curve I haven't done new benchmarking yet. This leads us to believe that in theory the lines would not cross for any value of n where AKS would finish before our sun burned out.

So our expectation is that standard AKS will always be slower than ECPP for almost all numbers it certainly has shown itself so for numbers up to 25k digits. AKS may have more improvements waiting to be discovered that makes it practical. This is a fundamental change, but shows how AKS opened up some new research areas. However, almost 10 years later I have not seen anyone use this method or even any implementations. My current impression is that the answer is no, but that further results [ Some of these algorithms can be easily parallelized or distributed.

AKS very easily each 's' test is independent. ECPP isn't too hard. In reality, no one uses these algorithms, since they are too slow. Instead, probabilistic primality testing algorithms are used, mainly Miller—Rabin, which is a modification of Miller's algorithm mentioned above another important algorithm is Solovay—Strassen.

In their comment, jbapple raises the issue of deciding which primality test to use in practice. This is a question of implementation and benchmarking: implement and optimize a few algorithms, and experimentally determine which is fastest in which range. For the curious, the coders of PARI did just that, and they came up with a deterministic function isprime and a probabilistic function ispseudoprime , both of which can be found here.

The probabilistic test used is Miller—Rabin. The deterministic one is BPSW. Here is more information from Dana Jacobsen :. Pari since version 2. Pari 2. Using isprime x,1 would do a Pocklington proof, which was fine for about 80 digits and then became too slow to be generally useful. You also write In reality, no one uses these algorithms, since they are too slow. I believe I know what you mean, but I think this is too strong depending on your audience. They are useful for paranoid crypto, and useful for people doing things like primegaps or factordb where one has enough time to want proven primes.

Only then, if at all, we run a deterministic test. In all of these tests, memory is not an issue. It is an issue for AKS. See, for instance, this eprint. Some of this depends on the implementation. If one implements what numberphile's video calls AKS which is actually a generalization of Fermat's Little Theorem , memory use will be extremely high.

Using an NTL implementation of the v1 or v6 algorithm like the referenced paper will result in stupid large amounts of memory. Using some of the Bernstein improvements and GMP binary segmentation leads to much better growth e.

Powerful algorithms too complex to implement tcs. Sign up to join this community. The best answers are voted up and rise to the top. Home Questions Tags Users Unanswered. When is the AKS primality test actually faster than other tests? Ask Question. Asked 6 years, 2 months ago. Active 1 year, 5 months ago. Viewed 9k times. Vortico Vortico 3 3 silver badges 5 5 bronze badges.

Active Oldest Votes. It is not currently of any practical use. Glorfindel 1 1 gold badge 6 6 silver badges 12 12 bronze badges.

DanaJ DanaJ 2 2 silver badges 9 9 bronze badges. Here is more information from Dana Jacobsen : Pari since version 2. They do take arguments which change the behavior: isprime x,0 default. Yuval Filmus Yuval Filmus k 18 18 gold badges silver badges bronze badges.

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## AKS Primality Test

The AKS algorithm for testing whether a number is prime is a polynomial-time algorithm based on an elementary theorem about Pascal triangles. These operators were implemented in Bracmat before all other operators! Some algebraic values can exist in two evaluated forms. This is used in the forceExpansion function to convert e. The primality test uses a pattern that looks for a fractional factor.

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## The AKS primality test

The proof is also notable for not relying on the field of analysis. AKS is the first primality-proving algorithm to be simultaneously general , polynomial , deterministic , and unconditional. Previous algorithms had been developed for centuries and achieved three of these properties at most, but not all four. While the algorithm is of immense theoretical importance, it is not used in practice, rendering it a galactic algorithm. For bit inputs, the Baillie—PSW primality test is deterministic and runs many orders of magnitude faster. Additionally, ECPP can output a primality certificate that allows independent and rapid verification of the results, which is not possible with the AKS algorithm.

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## AKS primality test

In August , M. Agrawal and colleagues announced a deterministic algorithm for determining if a number is prime that runs in polynomial time Agrawal et al. While this had long been believed possible Wagon , no one had previously been able to produce an explicit polynomial time deterministic algorithm although probabilistic algorithms were known that seem to run in polynomial time. Commenting on the impact of this discovery, P. Leyland noted, "One reason for the excitement within the mathematical community is not only does this algorithm settle a long-standing problem, it also does so in a brilliantly simple manner. Everyone is now wondering what else has been similarly overlooked" quoted by Crandall and Papadopoulos The complexity of the original algorithm of Agrawal et al.