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This proves that the algorithm to compute the Brauer group in [VAV] cannot be generalized in some cases."},"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":"1907.08810","kind":"arxiv","version":1},"metadata":{"license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","primary_cat":"math.NT","submitted_at":"2019-07-20T13:35:25Z","cross_cats_sorted":["math.AG"],"title_canon_sha256":"8969148014e9aa25a5fb01d3d5106025851deff263f77a6729f888f10bedeab8","abstract_canon_sha256":"2d0c01f69cfdf9718e09123426ba663fd1233621f80679fe26d099b2ff6c8574"},"schema_version":"1.0"},"receipt":{"kind":"pith_receipt","key_id":"pith-v1-2026-05","algorithm":"ed25519","signed_at":"2026-05-17T23:40:03.040001Z","signature_b64":"XgMBsXjJVnZwjp9xmXm8On9s2LvmwxSfUgWmReqNxpOsCTKAyl0Gm8Qok3p253rDXB4wAZjt+OD4qxM/BGhuDg==","signed_message":"canonical_sha256_bytes","builder_version":"pith-number-builder-2026-05-17-v1","receipt_version":"0.3","canonical_sha256":"820cad5be1426d4759e7163a7091010396e7acf300cc63a42ce7e8f9e2847654","last_reissued_at":"2026-05-17T23:40:03.039395Z","signature_status":"signed_v1","first_computed_at":"2026-05-17T23:40:03.039395Z","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54"},"graph_snapshot":{"paper":{"title":"Vanishing of the Brauer group of a del Pezzo surface of degree 4","license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","headline":"","cross_cats":["math.AG"],"primary_cat":"math.NT","authors_text":"Manar Riman","submitted_at":"2019-07-20T13:35:25Z","abstract_excerpt":"We explicitly construct a del Pezzo surface $X$ of degree 4 over a field $k$ such that $\\operatorname{H}^1(k,\\operatorname{Pic}\\overline X)$ is isomorphic to $\\mathbb{ZZ}/2\\mathbb{Z}$ while $\\operatorname{Br} X/\\operatorname{Br} k$ is trivial. 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