{"bundle_type":"pith_open_graph_bundle","bundle_version":"1.0","pith_number":"pith:2017:2XJR6XZLE7M5GJ7DI7QWW22CEQ","short_pith_number":"pith:2XJR6XZL","canonical_record":{"source":{"id":"1701.02118","kind":"arxiv","version":1},"metadata":{"license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","primary_cat":"cs.LO","submitted_at":"2017-01-09T10:07:50Z","cross_cats_sorted":[],"title_canon_sha256":"5039bfd869c09f218d2ed0c462d4adbea7adaf549c3c0a87b98a14a36be2dd0d","abstract_canon_sha256":"2334d386cfe32fb20a5cf3f8ed36680b7f32d17e735d444ca20e8801c7e1d788"},"schema_version":"1.0"},"canonical_sha256":"d5d31f5f2b27d9d327e347e16b6b42242afb7d0f7b66c763dec41664ac06445f","source":{"kind":"arxiv","id":"1701.02118","version":1},"source_aliases":[{"alias_kind":"arxiv","alias_value":"1701.02118","created_at":"2026-05-18T00:53:11Z"},{"alias_kind":"arxiv_version","alias_value":"1701.02118v1","created_at":"2026-05-18T00:53:11Z"},{"alias_kind":"doi","alias_value":"10.48550/arxiv.1701.02118","created_at":"2026-05-18T00:53:11Z"},{"alias_kind":"pith_short_12","alias_value":"2XJR6XZLE7M5","created_at":"2026-05-18T12:30:55Z"},{"alias_kind":"pith_short_16","alias_value":"2XJR6XZLE7M5GJ7D","created_at":"2026-05-18T12:30:55Z"},{"alias_kind":"pith_short_8","alias_value":"2XJR6XZL","created_at":"2026-05-18T12:30:55Z"}],"events":[{"event_type":"record_created","subject_pith_number":"pith:2017:2XJR6XZLE7M5GJ7DI7QWW22CEQ","target":"record","payload":{"canonical_record":{"source":{"id":"1701.02118","kind":"arxiv","version":1},"metadata":{"license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","primary_cat":"cs.LO","submitted_at":"2017-01-09T10:07:50Z","cross_cats_sorted":[],"title_canon_sha256":"5039bfd869c09f218d2ed0c462d4adbea7adaf549c3c0a87b98a14a36be2dd0d","abstract_canon_sha256":"2334d386cfe32fb20a5cf3f8ed36680b7f32d17e735d444ca20e8801c7e1d788"},"schema_version":"1.0"},"canonical_sha256":"d5d31f5f2b27d9d327e347e16b6b42242afb7d0f7b66c763dec41664ac06445f","receipt":{"kind":"pith_receipt","key_id":"pith-v1-2026-05","algorithm":"ed25519","signed_at":"2026-05-18T00:53:11.611392Z","signature_b64":"UzW9Yl18lu/rFEB+nZIX7zpxDNoRxUn4qo+P0Y8lQtmLCvASETC9W0St+PQCGMVvREDktdoDm7eBCxtuudofDg==","signed_message":"canonical_sha256_bytes","builder_version":"pith-number-builder-2026-05-17-v1","receipt_version":"0.3","canonical_sha256":"d5d31f5f2b27d9d327e347e16b6b42242afb7d0f7b66c763dec41664ac06445f","last_reissued_at":"2026-05-18T00:53:11.610925Z","signature_status":"signed_v1","first_computed_at":"2026-05-18T00:53:11.610925Z","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54"},"source_kind":"arxiv","source_id":"1701.02118","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":"2026-05-18T00:53:11Z","supersedes":[],"prev_event":null,"signature":{"signature_status":"signed_v1","algorithm":"ed25519","key_id":"pith-v1-2026-05","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54","signature_b64":"shS+H6pVjQFBc4hCQJV1+pODGsbOrw7fgot9QZ3cRZ3nt/mgqyN19koBi5Egd1VU0GdIyXJLA5Kcx2QnTPn/Bg==","signed_message":"open_graph_event_sha256_bytes","signed_at":"2026-05-31T18:50:48.823715Z"},"content_sha256":"b29dce3843841f7e674c932d485847bd2e86c24b3dda9a5211e050b0ebb77fd5","schema_version":"1.0","event_id":"sha256:b29dce3843841f7e674c932d485847bd2e86c24b3dda9a5211e050b0ebb77fd5"},{"event_type":"graph_snapshot","subject_pith_number":"pith:2017:2XJR6XZLE7M5GJ7DI7QWW22CEQ","target":"graph","payload":{"graph_snapshot":{"paper":{"title":"Type homogeneity is not a restriction for safe recursion schemes","license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","headline":"","cross_cats":[],"primary_cat":"cs.LO","authors_text":"William Blum","submitted_at":"2017-01-09T10:07:50Z","abstract_excerpt":"Knapik et al. introduced the safety restriction which constrains both the types and syntax of the production rules defining a higher-order recursion scheme. This restriction gives rise to an equi-expressivity result between order-n pushdown automata and order-n safe recursion schemes, when such devices are used as tree generators. We show that the typing constraint of safety, called homogeneity, is unnecessary in the sense that imposing the syntactic restriction alone is sufficient to prove the equi-expressivity result for trees."},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"1701.02118","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":"2026-05-18T00:53:11Z","supersedes":[],"prev_event":null,"signature":{"signature_status":"signed_v1","algorithm":"ed25519","key_id":"pith-v1-2026-05","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54","signature_b64":"YuLFU7dfmbTWjU5CD2eE7hM55U8Yy7eysH9Bg8FrQHV4E4Ish25dXO5NsNNWd0YoY55FK0e27Rh2tqa7mICdAw==","signed_message":"open_graph_event_sha256_bytes","signed_at":"2026-05-31T18:50:48.824434Z"},"content_sha256":"aef22b5faceefd10a288b2493784295a1d9f9fa368f8f141010301913a9e39ad","schema_version":"1.0","event_id":"sha256:aef22b5faceefd10a288b2493784295a1d9f9fa368f8f141010301913a9e39ad"}],"timestamp_proofs":[],"mirror_hints":[{"mirror_type":"https","name":"Pith Resolver","base_url":"https://pith.science","bundle_url":"https://pith.science/pith/2XJR6XZLE7M5GJ7DI7QWW22CEQ/bundle.json","state_url":"https://pith.science/pith/2XJR6XZLE7M5GJ7DI7QWW22CEQ/state.json","well_known_bundle_url":"https://pith.science/.well-known/pith/2XJR6XZLE7M5GJ7DI7QWW22CEQ/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":"2026-05-31T18:50:48Z","links":{"resolver":"https://pith.science/pith/2XJR6XZLE7M5GJ7DI7QWW22CEQ","bundle":"https://pith.science/pith/2XJR6XZLE7M5GJ7DI7QWW22CEQ/bundle.json","state":"https://pith.science/pith/2XJR6XZLE7M5GJ7DI7QWW22CEQ/state.json","well_known_bundle":"https://pith.science/.well-known/pith/2XJR6XZLE7M5GJ7DI7QWW22CEQ/bundle.json"},"state":{"state_type":"pith_open_graph_state","state_version":"1.0","pith_number":"pith:2017:2XJR6XZLE7M5GJ7DI7QWW22CEQ","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":"2334d386cfe32fb20a5cf3f8ed36680b7f32d17e735d444ca20e8801c7e1d788","cross_cats_sorted":[],"license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","primary_cat":"cs.LO","submitted_at":"2017-01-09T10:07:50Z","title_canon_sha256":"5039bfd869c09f218d2ed0c462d4adbea7adaf549c3c0a87b98a14a36be2dd0d"},"schema_version":"1.0","source":{"id":"1701.02118","kind":"arxiv","version":1}},"source_aliases":[{"alias_kind":"arxiv","alias_value":"1701.02118","created_at":"2026-05-18T00:53:11Z"},{"alias_kind":"arxiv_version","alias_value":"1701.02118v1","created_at":"2026-05-18T00:53:11Z"},{"alias_kind":"doi","alias_value":"10.48550/arxiv.1701.02118","created_at":"2026-05-18T00:53:11Z"},{"alias_kind":"pith_short_12","alias_value":"2XJR6XZLE7M5","created_at":"2026-05-18T12:30:55Z"},{"alias_kind":"pith_short_16","alias_value":"2XJR6XZLE7M5GJ7D","created_at":"2026-05-18T12:30:55Z"},{"alias_kind":"pith_short_8","alias_value":"2XJR6XZL","created_at":"2026-05-18T12:30:55Z"}],"graph_snapshots":[{"event_id":"sha256:aef22b5faceefd10a288b2493784295a1d9f9fa368f8f141010301913a9e39ad","target":"graph","created_at":"2026-05-18T00:53:11Z","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":"Knapik et al. introduced the safety restriction which constrains both the types and syntax of the production rules defining a higher-order recursion scheme. This restriction gives rise to an equi-expressivity result between order-n pushdown automata and order-n safe recursion schemes, when such devices are used as tree generators. We show that the typing constraint of safety, called homogeneity, is unnecessary in the sense that imposing the syntactic restriction alone is sufficient to prove the equi-expressivity result for trees.","authors_text":"William Blum","cross_cats":[],"headline":"","license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","primary_cat":"cs.LO","submitted_at":"2017-01-09T10:07:50Z","title":"Type homogeneity is not a restriction for safe recursion schemes"},"references":{"count":0,"internal_anchors":0,"resolved_work":0,"sample":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"1701.02118","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:b29dce3843841f7e674c932d485847bd2e86c24b3dda9a5211e050b0ebb77fd5","target":"record","created_at":"2026-05-18T00:53:11Z","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":"2334d386cfe32fb20a5cf3f8ed36680b7f32d17e735d444ca20e8801c7e1d788","cross_cats_sorted":[],"license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","primary_cat":"cs.LO","submitted_at":"2017-01-09T10:07:50Z","title_canon_sha256":"5039bfd869c09f218d2ed0c462d4adbea7adaf549c3c0a87b98a14a36be2dd0d"},"schema_version":"1.0","source":{"id":"1701.02118","kind":"arxiv","version":1}},"canonical_sha256":"d5d31f5f2b27d9d327e347e16b6b42242afb7d0f7b66c763dec41664ac06445f","receipt":{"algorithm":"ed25519","builder_version":"pith-number-builder-2026-05-17-v1","canonical_sha256":"d5d31f5f2b27d9d327e347e16b6b42242afb7d0f7b66c763dec41664ac06445f","first_computed_at":"2026-05-18T00:53:11.610925Z","key_id":"pith-v1-2026-05","kind":"pith_receipt","last_reissued_at":"2026-05-18T00:53:11.610925Z","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54","receipt_version":"0.3","signature_b64":"UzW9Yl18lu/rFEB+nZIX7zpxDNoRxUn4qo+P0Y8lQtmLCvASETC9W0St+PQCGMVvREDktdoDm7eBCxtuudofDg==","signature_status":"signed_v1","signed_at":"2026-05-18T00:53:11.611392Z","signed_message":"canonical_sha256_bytes"},"source_id":"1701.02118","source_kind":"arxiv","source_version":1}}},"equivocations":[],"invalid_events":[],"applied_event_ids":["sha256:b29dce3843841f7e674c932d485847bd2e86c24b3dda9a5211e050b0ebb77fd5","sha256:aef22b5faceefd10a288b2493784295a1d9f9fa368f8f141010301913a9e39ad"],"state_sha256":"0fc5d7c4e4ae9b9efd59ea6fd04468a570c268fa695f42ab4dfe99342ad03690"},"bundle_signature":{"signature_status":"signed_v1","algorithm":"ed25519","key_id":"pith-v1-2026-05","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54","signature_b64":"ObGhG6Qfgh1XkRYNHfgkMpb02YApYgnFhqVIEB6nvRkZWUDLj9M5ZIE69hrrHqjt1plj5GPn59j1xscUrf/fDA==","signed_message":"bundle_sha256_bytes","signed_at":"2026-05-31T18:50:48.828563Z","bundle_sha256":"973d5ba4e52a0197bfac879fc777fdbbc59cd8961e15f6ee3c74f80f9260e298"}}