Austin's common fixed-point conjecture for commuting contractions

Let (X,d)(X,d) be a complete metric space, let rr be a positive integer, and let λ(0,1)\lambda\in(0,1). A map f:XXf:X\to X is a λ\lambda-contraction if

d(f(x),f(y))λd(x,y)d(f(x),f(y))\leq\lambda d(x,y)

for all x,yXx,y\in X. The maps f1,,frf_1,\ldots,f_r pairwise commute if fifj=fjfif_i\circ f_j=f_j\circ f_i for all i,ji,j.

Austin's conjecture. If {f1,,fr}\{f_1,\ldots,f_r\} is a pairwise commuting family of λ\lambda-contractions on XX, then the maps have a common fixed point; that is, there exists xXx\in X such that fi(x)=xf_i(x)=x for every ii.

The source reports that Austin proved the case r=2r=2, while Milićević proved the case r=3r=3 and the case of sufficiently small λ\lambda; the general statement remains open.

Sources & referencesView supporting material

Primary source

Alexey Pokrovskiy, “Bounded diameter monochromatic component covers”, arXiv:2507.05842 (2026).

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