{"bundle_type":"pith_open_graph_bundle","bundle_version":"1.0","pith_number":"pith:2019:NXBOJZDFNJYEUCNO6RTIXA3OEW","short_pith_number":"pith:NXBOJZDF","canonical_record":{"source":{"id":"1907.04620","kind":"arxiv","version":1},"metadata":{"license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","primary_cat":"stat.ME","submitted_at":"2019-07-10T11:16:05Z","cross_cats_sorted":["stat.CO"],"title_canon_sha256":"5a17f48a9314bdca8abffe9a79e6d8b184a1b66c4674a0a67b9e92c29f7478b6","abstract_canon_sha256":"b2adcae5722f3485ae35b347d7ed2ab467c21411aa7c292b82ce5d3721f9b858"},"schema_version":"1.0"},"canonical_sha256":"6dc2e4e4656a704a09aef4668b836e25a428c1dd5dc54b29c29afdd84d49c29b","source":{"kind":"arxiv","id":"1907.04620","version":1},"source_aliases":[{"alias_kind":"arxiv","alias_value":"1907.04620","created_at":"2026-05-17T23:40:57Z"},{"alias_kind":"arxiv_version","alias_value":"1907.04620v1","created_at":"2026-05-17T23:40:57Z"},{"alias_kind":"doi","alias_value":"10.48550/arxiv.1907.04620","created_at":"2026-05-17T23:40:57Z"},{"alias_kind":"pith_short_12","alias_value":"NXBOJZDFNJYE","created_at":"2026-05-18T12:33:24Z"},{"alias_kind":"pith_short_16","alias_value":"NXBOJZDFNJYEUCNO","created_at":"2026-05-18T12:33:24Z"},{"alias_kind":"pith_short_8","alias_value":"NXBOJZDF","created_at":"2026-05-18T12:33:24Z"}],"events":[{"event_type":"record_created","subject_pith_number":"pith:2019:NXBOJZDFNJYEUCNO6RTIXA3OEW","target":"record","payload":{"canonical_record":{"source":{"id":"1907.04620","kind":"arxiv","version":1},"metadata":{"license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","primary_cat":"stat.ME","submitted_at":"2019-07-10T11:16:05Z","cross_cats_sorted":["stat.CO"],"title_canon_sha256":"5a17f48a9314bdca8abffe9a79e6d8b184a1b66c4674a0a67b9e92c29f7478b6","abstract_canon_sha256":"b2adcae5722f3485ae35b347d7ed2ab467c21411aa7c292b82ce5d3721f9b858"},"schema_version":"1.0"},"canonical_sha256":"6dc2e4e4656a704a09aef4668b836e25a428c1dd5dc54b29c29afdd84d49c29b","receipt":{"kind":"pith_receipt","key_id":"pith-v1-2026-05","algorithm":"ed25519","signed_at":"2026-05-17T23:40:57.344095Z","signature_b64":"Qysu+tCekVC1dYr3EjIYcn3Nmhkep88G2Iafc9DjkaLetHzIpyfY3Xlo6i9IpJBMox0IHv7KGVZTSR31jg/GAQ==","signed_message":"canonical_sha256_bytes","builder_version":"pith-number-builder-2026-05-17-v1","receipt_version":"0.3","canonical_sha256":"6dc2e4e4656a704a09aef4668b836e25a428c1dd5dc54b29c29afdd84d49c29b","last_reissued_at":"2026-05-17T23:40:57.343456Z","signature_status":"signed_v1","first_computed_at":"2026-05-17T23:40:57.343456Z","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54"},"source_kind":"arxiv","source_id":"1907.04620","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":"2026-05-17T23:40:57Z","supersedes":[],"prev_event":null,"signature":{"signature_status":"signed_v1","algorithm":"ed25519","key_id":"pith-v1-2026-05","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54","signature_b64":"BUHXTPSo0nxkT4+QDV0R3jJaBg5I2ZCveCXplsKjbNhu56vrW2oe5LjWhBSVwisa39DdfMvIpRpVtL0ZgrNJCw==","signed_message":"open_graph_event_sha256_bytes","signed_at":"2026-05-25T13:45:20.919108Z"},"content_sha256":"b9a32d105a2ba5fa7e00db5ef46ffb8ae4ef67a96b29c977513d9b9cfc0f67f4","schema_version":"1.0","event_id":"sha256:b9a32d105a2ba5fa7e00db5ef46ffb8ae4ef67a96b29c977513d9b9cfc0f67f4"},{"event_type":"graph_snapshot","subject_pith_number":"pith:2019:NXBOJZDFNJYEUCNO6RTIXA3OEW","target":"graph","payload":{"graph_snapshot":{"paper":{"title":"Sparse Unit-Sum Regression","license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","headline":"","cross_cats":["stat.CO"],"primary_cat":"stat.ME","authors_text":"Nick Koning, Paul Bekker","submitted_at":"2019-07-10T11:16:05Z","abstract_excerpt":"This paper considers sparsity in linear regression under the restriction that the regression weights sum to one. We propose an approach that combines $\\ell_0$- and $\\ell_1$-regularization. We compute its solution by adapting a recent methodological innovation made by Bertsimas et al. (2016) for $\\ell_0$-regularization in standard linear regression. In a simulation experiment we compare our approach to $\\ell_0$-regularization and $\\ell_1$-regularization and find that it performs favorably in terms of predictive performance and sparsity. In an application to index tracking we show that our appro"},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"1907.04620","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":"2026-05-17T23:40:57Z","supersedes":[],"prev_event":null,"signature":{"signature_status":"signed_v1","algorithm":"ed25519","key_id":"pith-v1-2026-05","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54","signature_b64":"ngieh9v+bw+zlm0RS5mlFYfL55xMjhGVz3BTJ6/gMOMYW2jbEHY5L+vXcibSs2j8V/0P7MIoATuuabGPjVZKBQ==","signed_message":"open_graph_event_sha256_bytes","signed_at":"2026-05-25T13:45:20.919789Z"},"content_sha256":"a4d5370a708f3627e90ea776d88d87814d741bd60243b3dcdafebcd38fdf68fc","schema_version":"1.0","event_id":"sha256:a4d5370a708f3627e90ea776d88d87814d741bd60243b3dcdafebcd38fdf68fc"}],"timestamp_proofs":[],"mirror_hints":[{"mirror_type":"https","name":"Pith Resolver","base_url":"https://pith.science","bundle_url":"https://pith.science/pith/NXBOJZDFNJYEUCNO6RTIXA3OEW/bundle.json","state_url":"https://pith.science/pith/NXBOJZDFNJYEUCNO6RTIXA3OEW/state.json","well_known_bundle_url":"https://pith.science/.well-known/pith/NXBOJZDFNJYEUCNO6RTIXA3OEW/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":"2026-05-25T13:45:20Z","links":{"resolver":"https://pith.science/pith/NXBOJZDFNJYEUCNO6RTIXA3OEW","bundle":"https://pith.science/pith/NXBOJZDFNJYEUCNO6RTIXA3OEW/bundle.json","state":"https://pith.science/pith/NXBOJZDFNJYEUCNO6RTIXA3OEW/state.json","well_known_bundle":"https://pith.science/.well-known/pith/NXBOJZDFNJYEUCNO6RTIXA3OEW/bundle.json"},"state":{"state_type":"pith_open_graph_state","state_version":"1.0","pith_number":"pith:2019:NXBOJZDFNJYEUCNO6RTIXA3OEW","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":"b2adcae5722f3485ae35b347d7ed2ab467c21411aa7c292b82ce5d3721f9b858","cross_cats_sorted":["stat.CO"],"license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","primary_cat":"stat.ME","submitted_at":"2019-07-10T11:16:05Z","title_canon_sha256":"5a17f48a9314bdca8abffe9a79e6d8b184a1b66c4674a0a67b9e92c29f7478b6"},"schema_version":"1.0","source":{"id":"1907.04620","kind":"arxiv","version":1}},"source_aliases":[{"alias_kind":"arxiv","alias_value":"1907.04620","created_at":"2026-05-17T23:40:57Z"},{"alias_kind":"arxiv_version","alias_value":"1907.04620v1","created_at":"2026-05-17T23:40:57Z"},{"alias_kind":"doi","alias_value":"10.48550/arxiv.1907.04620","created_at":"2026-05-17T23:40:57Z"},{"alias_kind":"pith_short_12","alias_value":"NXBOJZDFNJYE","created_at":"2026-05-18T12:33:24Z"},{"alias_kind":"pith_short_16","alias_value":"NXBOJZDFNJYEUCNO","created_at":"2026-05-18T12:33:24Z"},{"alias_kind":"pith_short_8","alias_value":"NXBOJZDF","created_at":"2026-05-18T12:33:24Z"}],"graph_snapshots":[{"event_id":"sha256:a4d5370a708f3627e90ea776d88d87814d741bd60243b3dcdafebcd38fdf68fc","target":"graph","created_at":"2026-05-17T23:40:57Z","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":"This paper considers sparsity in linear regression under the restriction that the regression weights sum to one. We propose an approach that combines $\\ell_0$- and $\\ell_1$-regularization. We compute its solution by adapting a recent methodological innovation made by Bertsimas et al. (2016) for $\\ell_0$-regularization in standard linear regression. In a simulation experiment we compare our approach to $\\ell_0$-regularization and $\\ell_1$-regularization and find that it performs favorably in terms of predictive performance and sparsity. In an application to index tracking we show that our appro","authors_text":"Nick Koning, Paul Bekker","cross_cats":["stat.CO"],"headline":"","license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","primary_cat":"stat.ME","submitted_at":"2019-07-10T11:16:05Z","title":"Sparse Unit-Sum Regression"},"references":{"count":0,"internal_anchors":0,"resolved_work":0,"sample":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"1907.04620","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:b9a32d105a2ba5fa7e00db5ef46ffb8ae4ef67a96b29c977513d9b9cfc0f67f4","target":"record","created_at":"2026-05-17T23:40:57Z","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":"b2adcae5722f3485ae35b347d7ed2ab467c21411aa7c292b82ce5d3721f9b858","cross_cats_sorted":["stat.CO"],"license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","primary_cat":"stat.ME","submitted_at":"2019-07-10T11:16:05Z","title_canon_sha256":"5a17f48a9314bdca8abffe9a79e6d8b184a1b66c4674a0a67b9e92c29f7478b6"},"schema_version":"1.0","source":{"id":"1907.04620","kind":"arxiv","version":1}},"canonical_sha256":"6dc2e4e4656a704a09aef4668b836e25a428c1dd5dc54b29c29afdd84d49c29b","receipt":{"algorithm":"ed25519","builder_version":"pith-number-builder-2026-05-17-v1","canonical_sha256":"6dc2e4e4656a704a09aef4668b836e25a428c1dd5dc54b29c29afdd84d49c29b","first_computed_at":"2026-05-17T23:40:57.343456Z","key_id":"pith-v1-2026-05","kind":"pith_receipt","last_reissued_at":"2026-05-17T23:40:57.343456Z","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54","receipt_version":"0.3","signature_b64":"Qysu+tCekVC1dYr3EjIYcn3Nmhkep88G2Iafc9DjkaLetHzIpyfY3Xlo6i9IpJBMox0IHv7KGVZTSR31jg/GAQ==","signature_status":"signed_v1","signed_at":"2026-05-17T23:40:57.344095Z","signed_message":"canonical_sha256_bytes"},"source_id":"1907.04620","source_kind":"arxiv","source_version":1}}},"equivocations":[],"invalid_events":[],"applied_event_ids":["sha256:b9a32d105a2ba5fa7e00db5ef46ffb8ae4ef67a96b29c977513d9b9cfc0f67f4","sha256:a4d5370a708f3627e90ea776d88d87814d741bd60243b3dcdafebcd38fdf68fc"],"state_sha256":"b6aca729205be2ffdb797f1d5d4c38009087252e909bc83f1426e1d866f4a821"},"bundle_signature":{"signature_status":"signed_v1","algorithm":"ed25519","key_id":"pith-v1-2026-05","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54","signature_b64":"ISuuw+aNc0Z/DH5BqBqtCbbduzq48noPyV80e2MFe7LXyxr2V5yt6JzFIjcE2PY7UZPCrMTqnig5vtEvfNLeDg==","signed_message":"bundle_sha256_bytes","signed_at":"2026-05-25T13:45:20.923325Z","bundle_sha256":"a8d0defbc73d9403769dd5a27e26ebe1a4e17de19eeba8ba11142fc24fc3835e"}}