{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,2]],"date-time":"2026-05-02T01:58:15Z","timestamp":1777687095095,"version":"3.51.4"},"reference-count":0,"publisher":"SAGE Publications","issue":"1","license":[{"start":{"date-parts":[[2015,2,1]],"date-time":"2015-02-01T00:00:00Z","timestamp":1422748800000},"content-version":"tdm","delay-in-days":0,"URL":"https:\/\/journals.sagepub.com\/page\/policies\/text-and-data-mining-license"}],"content-domain":{"domain":["journals.sagepub.com"],"crossmark-restriction":true},"short-container-title":["Computability"],"published-print":{"date-parts":[[2015,2]]},"abstract":"<jats:p>\n                    We extend the recently introduced Luzin hierarchy of qcb\n                    <jats:sub>0<\/jats:sub>\n                    -spaces to all countable ordinals, obtaining in this way the hyperprojective hierarchy of qcb\n                    <jats:sub>0<\/jats:sub>\n                    -spaces. We generalize all main results for the former hierarchy to this larger hierarchy. In particular, we extend the Kleene\u2013Kreisel continuous functionals of finite types to the continuous functionals of countable types and relate them to the new hierarchy. We show that the category of hyperprojective qcb\n                    <jats:sub>0<\/jats:sub>\n                    -spaces has much better closure properties than the category of projective qcb\n                    <jats:sub>0<\/jats:sub>\n                    -spaces. As a result, there are natural examples of spaces that are hyperprojective but not projective.\n                  <\/jats:p>","DOI":"10.3233\/com-150031","type":"journal-article","created":{"date-parts":[[2019,12,2]],"date-time":"2019-12-02T15:00:30Z","timestamp":1575298830000},"page":"1-17","update-policy":"https:\/\/doi.org\/10.1177\/sage-journals-update-policy","source":"Crossref","is-referenced-by-count":5,"title":["Hyperprojective hierarchy of qcb\n                    <sub>0<\/sub>\n                    -spaces"],"prefix":"10.1177","volume":"4","author":[{"given":"Matthias","family":"Schr\u00f6der","sequence":"first","affiliation":[{"name":"Kurt G\u00f6del Research Center, University of Vienna, Vienna, Austria. E-mail: matthias.schroeder@cca-net.de"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Victor","family":"Selivanov","sequence":"additional","affiliation":[{"name":"A.P. Ershov Institute of Informatics Systems SB RAS, Novosibirsk, Russia. E-mail: vseliv@iis.nsk.su"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"179","published-online":{"date-parts":[[2015,2,1]]},"container-title":["Computability"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/journals.sagepub.com\/doi\/pdf\/10.3233\/COM-150031","content-type":"application\/pdf","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/journals.sagepub.com\/doi\/pdf\/10.3233\/COM-150031","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,4,28]],"date-time":"2026-04-28T16:03:11Z","timestamp":1777392191000},"score":1,"resource":{"primary":{"URL":"https:\/\/journals.sagepub.com\/doi\/full\/10.3233\/COM-150031"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2015,2]]},"references-count":0,"journal-issue":{"issue":"1","published-print":{"date-parts":[[2015,2]]}},"alternative-id":["10.3233\/COM-150031"],"URL":"https:\/\/doi.org\/10.3233\/com-150031","relation":{},"ISSN":["2211-3568","2211-3576"],"issn-type":[{"value":"2211-3568","type":"print"},{"value":"2211-3576","type":"electronic"}],"subject":[],"published":{"date-parts":[[2015,2]]}}}