{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"204d08b2f53bb40e8be618b9fe04e23d73868dc581afa0efeceea1c92f26c438","created":"2026-10-15T23:43:22Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["ce59fb6cd812fc05906d0c60a71c75ea22bc686bcf38e7c3ef7010834d98ee7b","f26a81b4a548265a6a5c5a0e8138b756365a325a1883942cb78dd6e012274834"],"salt":"07f3408ec2893ac4728114163ea3947b7ccb4c6ad04bfc292c529f655b96fe55","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"classification","assisted_by":[],"external_id":"bio.ecosystem-statphys.lv-phase-diagram","kind":"well-posed","literature_status":"partially-resolved","n":"2","parents":[],"plain":"In the standard model of many interacting species with random interaction strengths, weak interactions lead every community to the same single steady state. Beyond a threshold strength the behavior changes, and it is not settled whether the community then has many possible steady states, keeps fluctuating chaotically, or both.","posed_since":"","precise":"Consider $dN_{i}/dt=N_{i}(1-N_{i}-\\sum_{j}\\alpha_{ij}N_{j})+\\lambda$, $i=1..S$, with $\\alpha_{ij}$ of mean $\\mu/S$, standard deviation $\\sigma/\\sqrt{S}$, correlation $\\gamma$ between $\\alpha_{ij}$ and $\\alpha_{ji}$, and immigration $\\lambda$. Dynamical mean-field theory gives a unique globally attracting fixed point for $\\sigma<\\sigma_{c}=\\sqrt{2}/(1+\\gamma)$ as $S\\to\\infty$. Classify the phases for $\\sigma>\\sigma_{c}$ as functions of $\\gamma$ in $[-1,1]$ and $\\mu$, with $\\lambda\\to 0$: number and stability of fixed points, presence of chaos or aging, and whether the transitions are sharp. An answer is a phase diagram with order parameters, derived or established numerically at large $S$.","problem_ref":"f26a81b4a548265a6a5c5a0e8138b756365a325a1883942cb78dd6e012274834","references":"","settled_by":"A dynamical mean-field or replica analysis, confirmed by large-$S$ simulations, that gives the phase boundaries and characterizes each phase for all $\\gamma$.","status_note":"The typical number of equilibria was computed in 2023 and found exponential in $S$; a 2026 preprint distinguishes two kinds of multiple-equilibria phase, and the chaotic region for $\\gamma < 1$ is not fully mapped.","title":"Phase diagram of random many-species Lotka-Volterra dynamics beyond stability","topic_ref":null},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"77d574dd735a29b0af7d1df8391c163e8bace46b90fdd97c7a68d310136fb58f","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"740c982bd120269fb139572ef2e991c80c0a5c45ae7bb10e006edddce7c42c60","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"MGWhh08cFJGv1FOMiqm32LkdI9hRvc-cZ8fvwCjIIzZTL-RKCeEzqnG7_GiAk95PaVpeSzAO5EIfL5kXq7ibDg"},"schema":"pubphys.envelope/1"},"record_hash":"77d574dd735a29b0af7d1df8391c163e8bace46b90fdd97c7a68d310136fb58f","leaf_index":2560}