{"bundle_type":"pith_open_graph_bundle","bundle_version":"1.0","pith_number":"pith:2019:NZ6BYF5GCXSRWV6OVYIWNMH4P4","short_pith_number":"pith:NZ6BYF5G","canonical_record":{"source":{"id":"1902.00877","kind":"arxiv","version":1},"metadata":{"license":"http://creativecommons.org/licenses/by/4.0/","primary_cat":"math.OC","submitted_at":"2019-02-03T10:55:47Z","cross_cats_sorted":[],"title_canon_sha256":"04ce2f7609f89187400fdce1d5d9dbd89497e8fcab56536f6cdb87a1e10428f0","abstract_canon_sha256":"67b300171102a26535f546f58421f9b87d531e8cfde1947c72719f711578ad24"},"schema_version":"1.0"},"canonical_sha256":"6e7c1c17a615e51b57ceae1166b0fc7f180f871c7b124fb73a93011fef0c754b","source":{"kind":"arxiv","id":"1902.00877","version":1},"source_aliases":[{"alias_kind":"arxiv","alias_value":"1902.00877","created_at":"2026-05-17T23:54:51Z"},{"alias_kind":"arxiv_version","alias_value":"1902.00877v1","created_at":"2026-05-17T23:54:51Z"},{"alias_kind":"doi","alias_value":"10.48550/arxiv.1902.00877","created_at":"2026-05-17T23:54:51Z"},{"alias_kind":"pith_short_12","alias_value":"NZ6BYF5GCXSR","created_at":"2026-05-18T12:33:24Z"},{"alias_kind":"pith_short_16","alias_value":"NZ6BYF5GCXSRWV6O","created_at":"2026-05-18T12:33:24Z"},{"alias_kind":"pith_short_8","alias_value":"NZ6BYF5G","created_at":"2026-05-18T12:33:24Z"}],"events":[{"event_type":"record_created","subject_pith_number":"pith:2019:NZ6BYF5GCXSRWV6OVYIWNMH4P4","target":"record","payload":{"canonical_record":{"source":{"id":"1902.00877","kind":"arxiv","version":1},"metadata":{"license":"http://creativecommons.org/licenses/by/4.0/","primary_cat":"math.OC","submitted_at":"2019-02-03T10:55:47Z","cross_cats_sorted":[],"title_canon_sha256":"04ce2f7609f89187400fdce1d5d9dbd89497e8fcab56536f6cdb87a1e10428f0","abstract_canon_sha256":"67b300171102a26535f546f58421f9b87d531e8cfde1947c72719f711578ad24"},"schema_version":"1.0"},"canonical_sha256":"6e7c1c17a615e51b57ceae1166b0fc7f180f871c7b124fb73a93011fef0c754b","receipt":{"kind":"pith_receipt","key_id":"pith-v1-2026-05","algorithm":"ed25519","signed_at":"2026-05-17T23:54:51.890383Z","signature_b64":"wxHQt1VIE1vjMfYvaDspjNhpLWw0d7d+bvZIANwpgM58H2ljGwQCcQLGGWd/Lf89nMheDtOvkDs5BcQYG7dRCA==","signed_message":"canonical_sha256_bytes","builder_version":"pith-number-builder-2026-05-17-v1","receipt_version":"0.3","canonical_sha256":"6e7c1c17a615e51b57ceae1166b0fc7f180f871c7b124fb73a93011fef0c754b","last_reissued_at":"2026-05-17T23:54:51.889861Z","signature_status":"signed_v1","first_computed_at":"2026-05-17T23:54:51.889861Z","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54"},"source_kind":"arxiv","source_id":"1902.00877","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":"2026-05-17T23:54:51Z","supersedes":[],"prev_event":null,"signature":{"signature_status":"signed_v1","algorithm":"ed25519","key_id":"pith-v1-2026-05","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54","signature_b64":"4YBzmeFYQSvcJ90elWYxFfwqh87w8LoJ6kZpjL+kY1YTNnPzaNRHRFNJnNyaqNaBIX0WQt5O1eCQsnL7bZiMDw==","signed_message":"open_graph_event_sha256_bytes","signed_at":"2026-06-25T18:30:01.373044Z"},"content_sha256":"50f182b7a98f32a73dcbf63e02ce61107feec995d3a9e66583c271acbe6695e2","schema_version":"1.0","event_id":"sha256:50f182b7a98f32a73dcbf63e02ce61107feec995d3a9e66583c271acbe6695e2"},{"event_type":"graph_snapshot","subject_pith_number":"pith:2019:NZ6BYF5GCXSRWV6OVYIWNMH4P4","target":"graph","payload":{"graph_snapshot":{"paper":{"title":"Topology Optimization with Bilevel Knapsack: An Efficient 51 Lines MATLAB Code","license":"http://creativecommons.org/licenses/by/4.0/","headline":"","cross_cats":[],"primary_cat":"math.OC","authors_text":"Vittorio Latorre","submitted_at":"2019-02-03T10:55:47Z","abstract_excerpt":"This paper presents an efficient 51 lines Matlab code to solve topology optimization problems. By the fact that the presented code is based on an hard 0-1 optimization method that handles the integer part of the optimization in a simple fashion and in sub-polynomial time, it has been possible to not only reduce the number of lines to 51 without sacrificing any readability, but also to obtain void-solid designs with close to none checkerboard patterns with improved efficiency. The numerical results in the paper show that the proposed method has the best average times compared to several codes a"},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"1902.00877","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":"2026-05-17T23:54:51Z","supersedes":[],"prev_event":null,"signature":{"signature_status":"signed_v1","algorithm":"ed25519","key_id":"pith-v1-2026-05","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54","signature_b64":"nyzC5Ea1CBBIqTa5KWjaA0cQ82vPD6apYkKDqcVChKT+/LngtHkKBechFdxPWEIvRmg+EAWHw3N16EYLS/EZCA==","signed_message":"open_graph_event_sha256_bytes","signed_at":"2026-06-25T18:30:01.373657Z"},"content_sha256":"7bdc4e59e83d09fd883a346b9eef1caf8a8defb0e2b2c0e9b40bc6ade173699d","schema_version":"1.0","event_id":"sha256:7bdc4e59e83d09fd883a346b9eef1caf8a8defb0e2b2c0e9b40bc6ade173699d"}],"timestamp_proofs":[],"mirror_hints":[{"mirror_type":"https","name":"Pith Resolver","base_url":"https://pith.science","bundle_url":"https://pith.science/pith/NZ6BYF5GCXSRWV6OVYIWNMH4P4/bundle.json","state_url":"https://pith.science/pith/NZ6BYF5GCXSRWV6OVYIWNMH4P4/state.json","well_known_bundle_url":"https://pith.science/.well-known/pith/NZ6BYF5GCXSRWV6OVYIWNMH4P4/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":"2026-06-25T18:30:01Z","links":{"resolver":"https://pith.science/pith/NZ6BYF5GCXSRWV6OVYIWNMH4P4","bundle":"https://pith.science/pith/NZ6BYF5GCXSRWV6OVYIWNMH4P4/bundle.json","state":"https://pith.science/pith/NZ6BYF5GCXSRWV6OVYIWNMH4P4/state.json","well_known_bundle":"https://pith.science/.well-known/pith/NZ6BYF5GCXSRWV6OVYIWNMH4P4/bundle.json"},"state":{"state_type":"pith_open_graph_state","state_version":"1.0","pith_number":"pith:2019:NZ6BYF5GCXSRWV6OVYIWNMH4P4","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":"67b300171102a26535f546f58421f9b87d531e8cfde1947c72719f711578ad24","cross_cats_sorted":[],"license":"http://creativecommons.org/licenses/by/4.0/","primary_cat":"math.OC","submitted_at":"2019-02-03T10:55:47Z","title_canon_sha256":"04ce2f7609f89187400fdce1d5d9dbd89497e8fcab56536f6cdb87a1e10428f0"},"schema_version":"1.0","source":{"id":"1902.00877","kind":"arxiv","version":1}},"source_aliases":[{"alias_kind":"arxiv","alias_value":"1902.00877","created_at":"2026-05-17T23:54:51Z"},{"alias_kind":"arxiv_version","alias_value":"1902.00877v1","created_at":"2026-05-17T23:54:51Z"},{"alias_kind":"doi","alias_value":"10.48550/arxiv.1902.00877","created_at":"2026-05-17T23:54:51Z"},{"alias_kind":"pith_short_12","alias_value":"NZ6BYF5GCXSR","created_at":"2026-05-18T12:33:24Z"},{"alias_kind":"pith_short_16","alias_value":"NZ6BYF5GCXSRWV6O","created_at":"2026-05-18T12:33:24Z"},{"alias_kind":"pith_short_8","alias_value":"NZ6BYF5G","created_at":"2026-05-18T12:33:24Z"}],"graph_snapshots":[{"event_id":"sha256:7bdc4e59e83d09fd883a346b9eef1caf8a8defb0e2b2c0e9b40bc6ade173699d","target":"graph","created_at":"2026-05-17T23:54:51Z","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 presents an efficient 51 lines Matlab code to solve topology optimization problems. By the fact that the presented code is based on an hard 0-1 optimization method that handles the integer part of the optimization in a simple fashion and in sub-polynomial time, it has been possible to not only reduce the number of lines to 51 without sacrificing any readability, but also to obtain void-solid designs with close to none checkerboard patterns with improved efficiency. The numerical results in the paper show that the proposed method has the best average times compared to several codes a","authors_text":"Vittorio Latorre","cross_cats":[],"headline":"","license":"http://creativecommons.org/licenses/by/4.0/","primary_cat":"math.OC","submitted_at":"2019-02-03T10:55:47Z","title":"Topology Optimization with Bilevel Knapsack: An Efficient 51 Lines MATLAB Code"},"references":{"count":0,"internal_anchors":0,"resolved_work":0,"sample":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"1902.00877","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":"sha256:50f182b7a98f32a73dcbf63e02ce61107feec995d3a9e66583c271acbe6695e2","target":"record","created_at":"2026-05-17T23:54:51Z","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":"67b300171102a26535f546f58421f9b87d531e8cfde1947c72719f711578ad24","cross_cats_sorted":[],"license":"http://creativecommons.org/licenses/by/4.0/","primary_cat":"math.OC","submitted_at":"2019-02-03T10:55:47Z","title_canon_sha256":"04ce2f7609f89187400fdce1d5d9dbd89497e8fcab56536f6cdb87a1e10428f0"},"schema_version":"1.0","source":{"id":"1902.00877","kind":"arxiv","version":1}},"canonical_sha256":"6e7c1c17a615e51b57ceae1166b0fc7f180f871c7b124fb73a93011fef0c754b","receipt":{"algorithm":"ed25519","builder_version":"pith-number-builder-2026-05-17-v1","canonical_sha256":"6e7c1c17a615e51b57ceae1166b0fc7f180f871c7b124fb73a93011fef0c754b","first_computed_at":"2026-05-17T23:54:51.889861Z","key_id":"pith-v1-2026-05","kind":"pith_receipt","last_reissued_at":"2026-05-17T23:54:51.889861Z","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54","receipt_version":"0.3","signature_b64":"wxHQt1VIE1vjMfYvaDspjNhpLWw0d7d+bvZIANwpgM58H2ljGwQCcQLGGWd/Lf89nMheDtOvkDs5BcQYG7dRCA==","signature_status":"signed_v1","signed_at":"2026-05-17T23:54:51.890383Z","signed_message":"canonical_sha256_bytes"},"source_id":"1902.00877","source_kind":"arxiv","source_version":1}}},"equivocations":[],"invalid_events":[],"applied_event_ids":["sha256:50f182b7a98f32a73dcbf63e02ce61107feec995d3a9e66583c271acbe6695e2","sha256:7bdc4e59e83d09fd883a346b9eef1caf8a8defb0e2b2c0e9b40bc6ade173699d"],"state_sha256":"80a514b0940cbf686fb04faa05b0185f7b27295965b5bfd998d69e89309c54ef"},"bundle_signature":{"signature_status":"signed_v1","algorithm":"ed25519","key_id":"pith-v1-2026-05","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54","signature_b64":"Pn8mKm6INv01WzLJ0z6PYnBip1NaaF0Y+sBvVR+yX9GBONAMkjDpD5s/dFV06l1AyaCxnxbGNIiEvzsi6j9/AQ==","signed_message":"bundle_sha256_bytes","signed_at":"2026-06-25T18:30:01.376850Z","bundle_sha256":"e2fbdcdeecd3db425f8780ab7ff3df99d6c7e1388603a7e3bc782a96378eebd1"}}