Research output: Contribution to journal › Article › peer-review
Hyperprojective hierarchy of qcb0-spaces. / Schröder, Matthias; Selivanov, Victor.
In: Computability, Vol. 4, No. 1, 01.01.2015, p. 1-17.Research output: Contribution to journal › Article › peer-review
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TY - JOUR
T1 - Hyperprojective hierarchy of qcb0-spaces
AU - Schröder, Matthias
AU - Selivanov, Victor
PY - 2015/1/1
Y1 - 2015/1/1
N2 - We extend the recently introduced Luzin hierarchy of qcb0-spaces to all countable ordinals, obtaining in this way the hyperprojective hierarchy of qcb0-spaces. We generalize all main results for the former hierarchy to this larger hierarchy. In particular, we extend the Kleene-Kreisel 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 qcb0-spaces has much better closure properties than the category of projective qcb0-spaces. As a result, there are natural examples of spaces that are hyperprojective but not projective.
AB - We extend the recently introduced Luzin hierarchy of qcb0-spaces to all countable ordinals, obtaining in this way the hyperprojective hierarchy of qcb0-spaces. We generalize all main results for the former hierarchy to this larger hierarchy. In particular, we extend the Kleene-Kreisel 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 qcb0-spaces has much better closure properties than the category of projective qcb0-spaces. As a result, there are natural examples of spaces that are hyperprojective but not projective.
KW - Cartesian closed category
KW - continuous functionals of countable types
KW - Hyperprojective hierarchy
KW - qcb0-space
UR - http://www.scopus.com/inward/record.url?scp=85011083071&partnerID=8YFLogxK
U2 - 10.3233/COM-150031
DO - 10.3233/COM-150031
M3 - Article
AN - SCOPUS:85011083071
VL - 4
SP - 1
EP - 17
JO - Computability
JF - Computability
SN - 2211-3568
IS - 1
ER -
ID: 126986033