Conjecture on extinction and non-halting in multitype branching processes in a Markovian environment

Let G=(V,E)G=(V,E) be a finite directed graph. For each vertex vVv\in V, let SvS_v be a finite state space, let PvP_v be an irreducible stochastic transition matrix, and let RvR_v be a stochastic reproduction matrix describing the offspring sent to the out-neighbors of vv. Let πv\pi_v be the stationary distribution of PvP_v, let μvw(i)\mu_{vw}(i) be the mean number of offspring sent from vv to ww when the state of vv is ii, and define

Mvw:=iSvπv(i)μvw(i).M_{vw}:=\sum_{i\in S_v}\pi_v(i)\mu_{vw}(i).

Let μ\mu be the Perron–Frobenius eigenvalue of the matrix MM. Multitype BPME halting conjecture. If μ<1\mu<1, then the network halts almost surely for any initial state and population. If μ=1\mu=1 and there are no conserved quantities, then the network halts almost surely for any initial state and population. If μ>1\mu>1, then for sufficiently large initial population the network has a positive probability not to halt. The claim proposes a threshold criterion for almost-sure halting versus positive-probability non-halting in a network of branching processes in a Markovian environment. No resolution is supplied in the source.

Sources & referencesView supporting material

Primary source

Lila Greco and Lionel Levine, “Branching in a Markovian Environment”, arXiv:2106.11249 (2021).

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