has only finitely many solutions (a,b,c,m,n,k) with distinct triplets of values (am, bn, ck) where a, b, c are positive
coprime integers and m, n, k are positive integers satisfying
(2)
The inequality on m, n, and k is a necessary part of the conjecture. Without the inequality there would be infinitely many solutions, for instance with k = 1 (for any a, b, m, and n and with c = am + bn) or with m, n, and k all equal to two (for the infinitely many known
Pythagorean triples).
Known solutions
As of 2015 the following ten solutions to equation (1) which meet the criteria of equation (2) are known:[1]
(for to satisfy Eq. 2)
The first of these (1m + 23 = 32) is the only solution where one of a, b or c is 1, according to the
Catalan conjecture, proven in 2002 by
Preda Mihăilescu. While this case leads to infinitely many solutions of (1) (since one can pick any m for m > 6), these solutions only give a single triplet of values (am, bn, ck).
Partial results
It is known by the Darmon–Granville theorem, which uses
Faltings's theorem, that for any fixed choice of positive integers m, n and k satisfying (2), only finitely many coprime triples (a, b, c) solving (1) exist.[2][3]: p. 64 However, the full Fermat–Catalan conjecture is stronger as it allows for the exponents m, n and k to vary.
For a list of results for impossible combinations of exponents, see
Beal conjecture#Partial results. Beal's conjecture is true if and only if all Fermat–Catalan solutions have m = 2, n = 2, or k = 2.
See also
Sums of powers, a list of related conjectures and theorems