{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"16143bea7b8084cc223709c810ba94b99180013f62797612911767ee63517ab6","created":"2026-10-03T07:17:57Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["5475cf5dc5b1a72283d26dc95dc6e00d7ea4e00096a7c6492e409a1816eeb011"],"salt":"f1a043c22018baba47a003a621ff39356581773abc4a3258b25074cc7dd4abaa","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"identification","assisted_by":[],"external_id":"bio.collective-behavior.interaction-rules","kind":"well-posed","literature_status":"partially-resolved","n":"1","parents":[],"plain":"A bird could respond to all neighbors within a fixed distance, or to a fixed number of nearest neighbors whatever their distance. Field data favor the second for starlings, but why the number is about seven, and whether this holds across species, is open.","posed_since":"2008","precise":"Infer from 3D trajectory data the interaction kernel of birds, fish and insects: metric (range $r_c$), topological ($n_c$ nearest neighbors; $n_c \\sim 6\\ \\mathrm{to}\\ 7$ in starlings, Ballerini and co-workers, 2008) or visual-field based, using maximum-entropy or force-inference methods with model selection. Determine $n_c$ across species and the mechanism (perceptual limits, group-cohesion optimization) that sets it.","problem_ref":null,"references":"","settled_by":"Model selection on large trajectory data sets from several species showing which kernel fits and the measured $n_c$ or $r_c$ with uncertainties.","status_note":"","title":"Topological or metric interactions in animal groups","topic_ref":"169c237bb7dec2b851fb7b715df607d983a88bff09590a878223e10c99e9ed50"},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"5d2d05c6f5339cdde55c2c94293ff00178dc6d90eb95336c8bcee3aa9c104cfc","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"74fc8333bb4f5eb014a07149639e5be8fa39fe5f04c7ef006f526622f643fd75","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"4C_3R29KxAFMaiaxHC2CmkCBgABViIwGPNgcXlJfO1tEmmAC4dm1A5l4VTWFhTZVK1zE-Go4G0nyfjl8-BltBg"},"schema":"pubphys.envelope/1"},"record_hash":"5d2d05c6f5339cdde55c2c94293ff00178dc6d90eb95336c8bcee3aa9c104cfc","leaf_index":746}