{"bundle_type":"pith_open_graph_bundle","bundle_version":"1.0","pith_number":"pith:2018:ZRK4KSCYUELRRCJNSC6PZULVJR","short_pith_number":"pith:ZRK4KSCY","canonical_record":{"source":{"id":"1804.00855","kind":"arxiv","version":1},"metadata":{"license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","primary_cat":"physics.soc-ph","submitted_at":"2018-04-03T07:33:30Z","cross_cats_sorted":[],"title_canon_sha256":"9fc0a5b6e130434d4f1666a5379654666101ba19ef20375c0b532d70603e7efb","abstract_canon_sha256":"07bc037bdf47a758fe8c73740efe290016d3f59db29c54af9aa6a4210f6d162f"},"schema_version":"1.0"},"canonical_sha256":"cc55c54858a11718892d90bcfcd1754c7f59eeb637ddacc55e3ddc9f4335f63c","source":{"kind":"arxiv","id":"1804.00855","version":1},"source_aliases":[{"alias_kind":"arxiv","alias_value":"1804.00855","created_at":"2026-05-18T00:19:31Z"},{"alias_kind":"arxiv_version","alias_value":"1804.00855v1","created_at":"2026-05-18T00:19:31Z"},{"alias_kind":"doi","alias_value":"10.48550/arxiv.1804.00855","created_at":"2026-05-18T00:19:31Z"},{"alias_kind":"pith_short_12","alias_value":"ZRK4KSCYUELR","created_at":"2026-05-18T12:33:07Z"},{"alias_kind":"pith_short_16","alias_value":"ZRK4KSCYUELRRCJN","created_at":"2026-05-18T12:33:07Z"},{"alias_kind":"pith_short_8","alias_value":"ZRK4KSCY","created_at":"2026-05-18T12:33:07Z"}],"events":[{"event_type":"record_created","subject_pith_number":"pith:2018:ZRK4KSCYUELRRCJNSC6PZULVJR","target":"record","payload":{"canonical_record":{"source":{"id":"1804.00855","kind":"arxiv","version":1},"metadata":{"license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","primary_cat":"physics.soc-ph","submitted_at":"2018-04-03T07:33:30Z","cross_cats_sorted":[],"title_canon_sha256":"9fc0a5b6e130434d4f1666a5379654666101ba19ef20375c0b532d70603e7efb","abstract_canon_sha256":"07bc037bdf47a758fe8c73740efe290016d3f59db29c54af9aa6a4210f6d162f"},"schema_version":"1.0"},"canonical_sha256":"cc55c54858a11718892d90bcfcd1754c7f59eeb637ddacc55e3ddc9f4335f63c","receipt":{"kind":"pith_receipt","key_id":"pith-v1-2026-05","algorithm":"ed25519","signed_at":"2026-05-18T00:19:31.955124Z","signature_b64":"iO7SzovdeqlWSz6KcVbIQgwXecznOaU0nGswMk7HVQGru+t+qSMJXvYk96SgqNKiRgkbn3KABTkN9hOCDVLlBQ==","signed_message":"canonical_sha256_bytes","builder_version":"pith-number-builder-2026-05-17-v1","receipt_version":"0.3","canonical_sha256":"cc55c54858a11718892d90bcfcd1754c7f59eeb637ddacc55e3ddc9f4335f63c","last_reissued_at":"2026-05-18T00:19:31.954649Z","signature_status":"signed_v1","first_computed_at":"2026-05-18T00:19:31.954649Z","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54"},"source_kind":"arxiv","source_id":"1804.00855","source_version":1,"attestation_state":"computed"},"signer":{"signer_id":"pith.science","signer_type":"pith_registry","key_id":"pith-v1-2026-05","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54"},"created_at":"2026-05-18T00:19:31Z","supersedes":[],"prev_event":null,"signature":{"signature_status":"signed_v1","algorithm":"ed25519","key_id":"pith-v1-2026-05","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54","signature_b64":"0zFkst9VmirKdHB6lD/JPjp1Uq+PwJ0jMM4Nqiugq4oP8/XUNfJHSNyVNUKO7x7fmIBhxVBwQuY7F/AwrRiHBA==","signed_message":"open_graph_event_sha256_bytes","signed_at":"2026-06-01T14:44:28.472051Z"},"content_sha256":"b253070bfa05403f211a60fc698fa1bcd1afe8778bd21454917d8bdae604c4f8","schema_version":"1.0","event_id":"sha256:b253070bfa05403f211a60fc698fa1bcd1afe8778bd21454917d8bdae604c4f8"},{"event_type":"graph_snapshot","subject_pith_number":"pith:2018:ZRK4KSCYUELRRCJNSC6PZULVJR","target":"graph","payload":{"graph_snapshot":{"paper":{"title":"The spatial organization of the population density in cities","license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","headline":"","cross_cats":[],"primary_cat":"physics.soc-ph","authors_text":"Marc Barthelemy, Valerio Volpati","submitted_at":"2018-04-03T07:33:30Z","abstract_excerpt":"Although the average population density of a city is an extremely simple indicator, it is often used as a determinant factor for describing various aspects of urban phenomena. On the other hand, a plethora of different measures that aim at characterizing the urban form have been introduced in the literature, often with the risk of redundancy. Here, we argue that two measures are enough to capture a wealth of different forms of the population density. First, fluctuations of the local density can be very important and we should distinguish almost homogeneous cities from highly heterogeneous ones"},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"1804.00855","kind":"arxiv","version":1},"verdict":{"id":null,"model_set":{},"created_at":null,"strongest_claim":"","one_line_summary":"","pipeline_version":null,"weakest_assumption":"","pith_extraction_headline":""},"references":{"count":0,"sample":[],"resolved_work":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57","internal_anchors":0},"formal_canon":{"evidence_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"author_claims":{"count":0,"strong_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"builder_version":"pith-number-builder-2026-05-17-v1"},"verdict_id":null},"signer":{"signer_id":"pith.science","signer_type":"pith_registry","key_id":"pith-v1-2026-05","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54"},"created_at":"2026-05-18T00:19:31Z","supersedes":[],"prev_event":null,"signature":{"signature_status":"signed_v1","algorithm":"ed25519","key_id":"pith-v1-2026-05","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54","signature_b64":"909+++2Pmt2aTdQfLHWoyK3J20siEaxHDpK+YfuVtrtI0MeW6GmIERWcH4g8cYXAaY2pwv2pE9bLfZo3gHF8AA==","signed_message":"open_graph_event_sha256_bytes","signed_at":"2026-06-01T14:44:28.472410Z"},"content_sha256":"969126b49d2f39678b862dfb2c6fc19fb8210bbb424c7197d5da0d93267539ce","schema_version":"1.0","event_id":"sha256:969126b49d2f39678b862dfb2c6fc19fb8210bbb424c7197d5da0d93267539ce"}],"timestamp_proofs":[],"mirror_hints":[{"mirror_type":"https","name":"Pith Resolver","base_url":"https://pith.science","bundle_url":"https://pith.science/pith/ZRK4KSCYUELRRCJNSC6PZULVJR/bundle.json","state_url":"https://pith.science/pith/ZRK4KSCYUELRRCJNSC6PZULVJR/state.json","well_known_bundle_url":"https://pith.science/.well-known/pith/ZRK4KSCYUELRRCJNSC6PZULVJR/bundle.json","status":"primary"}],"public_keys":[{"key_id":"pith-v1-2026-05","algorithm":"ed25519","format":"raw","public_key_b64":"stVStoiQhXFxp4s2pdzPNoqVNBMojDU/fJ2db5S3CbM=","public_key_hex":"b2d552b68890857171a78b36a5dccf368a953413288c353f7c9d9d6f94b709b3","fingerprint_sha256_b32_first128bits":"RVFV5Z2OI2J3ZUO7ERDEBCYNKS","fingerprint_sha256_hex":"8d4b5ee74e4693bcd1df2446408b0d54","rotates_at":null,"url":"https://pith.science/pith-signing-key.json","notes":"Pith uses this Ed25519 key to sign canonical record SHA-256 digests. Verify with: ed25519_verify(public_key, message=canonical_sha256_bytes, signature=base64decode(signature_b64))."}],"merge_version":"pith-open-graph-merge-v1","built_at":"2026-06-01T14:44:28Z","links":{"resolver":"https://pith.science/pith/ZRK4KSCYUELRRCJNSC6PZULVJR","bundle":"https://pith.science/pith/ZRK4KSCYUELRRCJNSC6PZULVJR/bundle.json","state":"https://pith.science/pith/ZRK4KSCYUELRRCJNSC6PZULVJR/state.json","well_known_bundle":"https://pith.science/.well-known/pith/ZRK4KSCYUELRRCJNSC6PZULVJR/bundle.json"},"state":{"state_type":"pith_open_graph_state","state_version":"1.0","pith_number":"pith:2018:ZRK4KSCYUELRRCJNSC6PZULVJR","merge_version":"pith-open-graph-merge-v1","event_count":2,"valid_event_count":2,"invalid_event_count":0,"equivocation_count":0,"current":{"canonical_record":{"metadata":{"abstract_canon_sha256":"07bc037bdf47a758fe8c73740efe290016d3f59db29c54af9aa6a4210f6d162f","cross_cats_sorted":[],"license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","primary_cat":"physics.soc-ph","submitted_at":"2018-04-03T07:33:30Z","title_canon_sha256":"9fc0a5b6e130434d4f1666a5379654666101ba19ef20375c0b532d70603e7efb"},"schema_version":"1.0","source":{"id":"1804.00855","kind":"arxiv","version":1}},"source_aliases":[{"alias_kind":"arxiv","alias_value":"1804.00855","created_at":"2026-05-18T00:19:31Z"},{"alias_kind":"arxiv_version","alias_value":"1804.00855v1","created_at":"2026-05-18T00:19:31Z"},{"alias_kind":"doi","alias_value":"10.48550/arxiv.1804.00855","created_at":"2026-05-18T00:19:31Z"},{"alias_kind":"pith_short_12","alias_value":"ZRK4KSCYUELR","created_at":"2026-05-18T12:33:07Z"},{"alias_kind":"pith_short_16","alias_value":"ZRK4KSCYUELRRCJN","created_at":"2026-05-18T12:33:07Z"},{"alias_kind":"pith_short_8","alias_value":"ZRK4KSCY","created_at":"2026-05-18T12:33:07Z"}],"graph_snapshots":[{"event_id":"sha256:969126b49d2f39678b862dfb2c6fc19fb8210bbb424c7197d5da0d93267539ce","target":"graph","created_at":"2026-05-18T00:19:31Z","signer":{"key_id":"pith-v1-2026-05","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54","signer_id":"pith.science","signer_type":"pith_registry"},"payload":{"graph_snapshot":{"author_claims":{"count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57","strong_count":0},"builder_version":"pith-number-builder-2026-05-17-v1","claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"formal_canon":{"evidence_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"paper":{"abstract_excerpt":"Although the average population density of a city is an extremely simple indicator, it is often used as a determinant factor for describing various aspects of urban phenomena. On the other hand, a plethora of different measures that aim at characterizing the urban form have been introduced in the literature, often with the risk of redundancy. Here, we argue that two measures are enough to capture a wealth of different forms of the population density. First, fluctuations of the local density can be very important and we should distinguish almost homogeneous cities from highly heterogeneous ones","authors_text":"Marc Barthelemy, Valerio Volpati","cross_cats":[],"headline":"","license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","primary_cat":"physics.soc-ph","submitted_at":"2018-04-03T07:33:30Z","title":"The spatial organization of the population density in cities"},"references":{"count":0,"internal_anchors":0,"resolved_work":0,"sample":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"1804.00855","kind":"arxiv","version":1},"verdict":{"created_at":null,"id":null,"model_set":{},"one_line_summary":"","pipeline_version":null,"pith_extraction_headline":"","strongest_claim":"","weakest_assumption":""}},"verdict_id":null}}],"author_attestations":[],"timestamp_anchors":[],"storage_attestations":[],"citation_signatures":[],"replication_records":[],"corrections":[],"mirror_hints":[],"record_created":{"event_id":"sha256:b253070bfa05403f211a60fc698fa1bcd1afe8778bd21454917d8bdae604c4f8","target":"record","created_at":"2026-05-18T00:19:31Z","signer":{"key_id":"pith-v1-2026-05","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54","signer_id":"pith.science","signer_type":"pith_registry"},"payload":{"attestation_state":"computed","canonical_record":{"metadata":{"abstract_canon_sha256":"07bc037bdf47a758fe8c73740efe290016d3f59db29c54af9aa6a4210f6d162f","cross_cats_sorted":[],"license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","primary_cat":"physics.soc-ph","submitted_at":"2018-04-03T07:33:30Z","title_canon_sha256":"9fc0a5b6e130434d4f1666a5379654666101ba19ef20375c0b532d70603e7efb"},"schema_version":"1.0","source":{"id":"1804.00855","kind":"arxiv","version":1}},"canonical_sha256":"cc55c54858a11718892d90bcfcd1754c7f59eeb637ddacc55e3ddc9f4335f63c","receipt":{"algorithm":"ed25519","builder_version":"pith-number-builder-2026-05-17-v1","canonical_sha256":"cc55c54858a11718892d90bcfcd1754c7f59eeb637ddacc55e3ddc9f4335f63c","first_computed_at":"2026-05-18T00:19:31.954649Z","key_id":"pith-v1-2026-05","kind":"pith_receipt","last_reissued_at":"2026-05-18T00:19:31.954649Z","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54","receipt_version":"0.3","signature_b64":"iO7SzovdeqlWSz6KcVbIQgwXecznOaU0nGswMk7HVQGru+t+qSMJXvYk96SgqNKiRgkbn3KABTkN9hOCDVLlBQ==","signature_status":"signed_v1","signed_at":"2026-05-18T00:19:31.955124Z","signed_message":"canonical_sha256_bytes"},"source_id":"1804.00855","source_kind":"arxiv","source_version":1}}},"equivocations":[],"invalid_events":[],"applied_event_ids":["sha256:b253070bfa05403f211a60fc698fa1bcd1afe8778bd21454917d8bdae604c4f8","sha256:969126b49d2f39678b862dfb2c6fc19fb8210bbb424c7197d5da0d93267539ce"],"state_sha256":"9bb6b375cc42f85aa0afb9c172a21ef8f11adbc70fd4b97a53506fc060b52c22"},"bundle_signature":{"signature_status":"signed_v1","algorithm":"ed25519","key_id":"pith-v1-2026-05","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54","signature_b64":"hX40YZxaAwYouTyr/CMsKt5ewFs3eAoF28Y6Qu3OOj/eymf3W+C0/FNREnO8WMdBVnL/hzjOU49Zg79FJutwDg==","signed_message":"bundle_sha256_bytes","signed_at":"2026-06-01T14:44:28.474382Z","bundle_sha256":"62b4e8977b5e9f2fece56d0ef83e54ba65da25c49742f92899a6e5b0695ef40c"}}