{"record_type":"pith_number_record","schema_url":"https://pith.science/schemas/pith-number/v1.json","pith_number":"pith:2018:NZTT6VYSEQKXJG7DNJ6OXOSEWA","short_pith_number":"pith:NZTT6VYS","schema_version":"1.0","canonical_sha256":"6e673f57122415749be36a7cebba44b01740276c2a7e8ffbef96430627bb5139","source":{"kind":"arxiv","id":"1806.05657","version":1},"attestation_state":"computed","paper":{"title":"Losing at Checkers is Hard","license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","headline":"","cross_cats":[],"primary_cat":"cs.CC","authors_text":"(2) Department of Electrical, Computer Engineering, Erik D. Demaine (1), Jayson Lynch (1) ((1) MIT CSAIL, Jeffrey Bosboom (1), Martin L. Demaine (1), San Diego), Spencer Congero (2), University of California","submitted_at":"2018-06-14T17:28:51Z","abstract_excerpt":"We prove computational intractability of variants of checkers: (1) deciding whether there is a move that forces the other player to win in one move is NP-complete; (2) checkers where players must always be able to jump on their turn is PSPACE-complete; and (3) cooperative versions of (1) and (2) are NP-complete. We also give cooperative checkers puzzles whose solutions are the letters of the alphabet."},"verification_status":{"content_addressed":true,"pith_receipt":true,"author_attested":false,"weak_author_claims":0,"strong_author_claims":0,"externally_anchored":false,"storage_verified":false,"citation_signatures":0,"replication_records":0,"graph_snapshot":true,"references_resolved":false,"formal_links_present":false},"canonical_record":{"source":{"id":"1806.05657","kind":"arxiv","version":1},"metadata":{"license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","primary_cat":"cs.CC","submitted_at":"2018-06-14T17:28:51Z","cross_cats_sorted":[],"title_canon_sha256":"5161fdef247c9f94fcb3b500dba4b6b1deff7cfce5a80c547c99b5a17dfe9744","abstract_canon_sha256":"bf5f914be5c2a184c03154116aa074a9299533b3697c3ed58a6e44589a3a7c9f"},"schema_version":"1.0"},"receipt":{"kind":"pith_receipt","key_id":"pith-v1-2026-05","algorithm":"ed25519","signed_at":"2026-05-18T00:13:14.435216Z","signature_b64":"Dnj2bRUMiLOtgPB6GjZy7kqeyGebLBMTku6BS/d2C2XdcqcYtgDSrAEDkesMJuCuoNc1u3BdQ3FHxyL4LB73Dw==","signed_message":"canonical_sha256_bytes","builder_version":"pith-number-builder-2026-05-17-v1","receipt_version":"0.3","canonical_sha256":"6e673f57122415749be36a7cebba44b01740276c2a7e8ffbef96430627bb5139","last_reissued_at":"2026-05-18T00:13:14.434608Z","signature_status":"signed_v1","first_computed_at":"2026-05-18T00:13:14.434608Z","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54"},"graph_snapshot":{"paper":{"title":"Losing at Checkers is Hard","license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","headline":"","cross_cats":[],"primary_cat":"cs.CC","authors_text":"(2) Department of Electrical, Computer Engineering, Erik D. Demaine (1), Jayson Lynch (1) ((1) MIT CSAIL, Jeffrey Bosboom (1), Martin L. Demaine (1), San Diego), Spencer Congero (2), University of California","submitted_at":"2018-06-14T17:28:51Z","abstract_excerpt":"We prove computational intractability of variants of checkers: (1) deciding whether there is a move that forces the other player to win in one move is NP-complete; (2) checkers where players must always be able to jump on their turn is PSPACE-complete; and (3) cooperative versions of (1) and (2) are NP-complete. We also give cooperative checkers puzzles whose solutions are the letters of the alphabet."},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"1806.05657","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"},"aliases":[{"alias_kind":"arxiv","alias_value":"1806.05657","created_at":"2026-05-18T00:13:14.434689+00:00"},{"alias_kind":"arxiv_version","alias_value":"1806.05657v1","created_at":"2026-05-18T00:13:14.434689+00:00"},{"alias_kind":"doi","alias_value":"10.48550/arxiv.1806.05657","created_at":"2026-05-18T00:13:14.434689+00:00"},{"alias_kind":"pith_short_12","alias_value":"NZTT6VYSEQKX","created_at":"2026-05-18T12:32:40.477152+00:00"},{"alias_kind":"pith_short_16","alias_value":"NZTT6VYSEQKXJG7D","created_at":"2026-05-18T12:32:40.477152+00:00"},{"alias_kind":"pith_short_8","alias_value":"NZTT6VYS","created_at":"2026-05-18T12:32:40.477152+00:00"}],"events":[],"event_summary":{},"paper_claims":[],"inbound_citations":{"count":0,"internal_anchor_count":0,"sample":[]},"formal_canon":{"evidence_count":0,"sample":[],"anchors":[]},"links":{"html":"https://pith.science/pith/NZTT6VYSEQKXJG7DNJ6OXOSEWA","json":"https://pith.science/pith/NZTT6VYSEQKXJG7DNJ6OXOSEWA.json","graph_json":"https://pith.science/api/pith-number/NZTT6VYSEQKXJG7DNJ6OXOSEWA/graph.json","events_json":"https://pith.science/api/pith-number/NZTT6VYSEQKXJG7DNJ6OXOSEWA/events.json","paper":"https://pith.science/paper/NZTT6VYS"},"agent_actions":{"view_html":"https://pith.science/pith/NZTT6VYSEQKXJG7DNJ6OXOSEWA","download_json":"https://pith.science/pith/NZTT6VYSEQKXJG7DNJ6OXOSEWA.json","view_paper":"https://pith.science/paper/NZTT6VYS","resolve_alias":"https://pith.science/api/pith-number/resolve?arxiv=1806.05657&json=true","fetch_graph":"https://pith.science/api/pith-number/NZTT6VYSEQKXJG7DNJ6OXOSEWA/graph.json","fetch_events":"https://pith.science/api/pith-number/NZTT6VYSEQKXJG7DNJ6OXOSEWA/events.json","actions":{"anchor_timestamp":"https://pith.science/pith/NZTT6VYSEQKXJG7DNJ6OXOSEWA/action/timestamp_anchor","attest_storage":"https://pith.science/pith/NZTT6VYSEQKXJG7DNJ6OXOSEWA/action/storage_attestation","attest_author":"https://pith.science/pith/NZTT6VYSEQKXJG7DNJ6OXOSEWA/action/author_attestation","sign_citation":"https://pith.science/pith/NZTT6VYSEQKXJG7DNJ6OXOSEWA/action/citation_signature","submit_replication":"https://pith.science/pith/NZTT6VYSEQKXJG7DNJ6OXOSEWA/action/replication_record"}},"created_at":"2026-05-18T00:13:14.434689+00:00","updated_at":"2026-05-18T00:13:14.434689+00:00"}