Research output: Contribution to journal › Article › peer-review
WADGE-LIKE DEGREES OF BOREL BQO-VALUED FUNCTIONS. / Kihara, Takayuki; Selivanov, Victor.
In: Proceedings of the American Mathematical Society, Vol. 150, No. 9, 01.09.2022, p. 3989-4003.Research output: Contribution to journal › Article › peer-review
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TY - JOUR
T1 - WADGE-LIKE DEGREES OF BOREL BQO-VALUED FUNCTIONS
AU - Kihara, Takayuki
AU - Selivanov, Victor
PY - 2022/9/1
Y1 - 2022/9/1
N2 - We unite two well known generalisations of the Wadge theory. The first one considers more general reducing functions than the continuous functions in the classical case, and the second one extends Wadge reducibility from sets (i.e., {0,1}-valued functions) to Q-valued functions, for a better quasiorder Q. In this article, we consider more general reducibilities on the Q-valued functions and generalise some results of L. Motto Ros [J. Symbolic Logic 74 (2009), pp. 27-49] in the first direction and of T. Kihara and A. Montalbán [Trans. Amer. Math. Soc. 370 (2018), pp. 9025-9044] in the second direction: Our main result states that the structure of the Δ0α-degrees of Δ0α+γ-measurable Q-valued functions is isomorphic to the Δ0β-degrees of Δ0β+γ-measurable Q-valued functions, and these are isomorphic to the generalized homomorphism order on the γ-th iterated Q-labeled forests.
AB - We unite two well known generalisations of the Wadge theory. The first one considers more general reducing functions than the continuous functions in the classical case, and the second one extends Wadge reducibility from sets (i.e., {0,1}-valued functions) to Q-valued functions, for a better quasiorder Q. In this article, we consider more general reducibilities on the Q-valued functions and generalise some results of L. Motto Ros [J. Symbolic Logic 74 (2009), pp. 27-49] in the first direction and of T. Kihara and A. Montalbán [Trans. Amer. Math. Soc. 370 (2018), pp. 9025-9044] in the second direction: Our main result states that the structure of the Δ0α-degrees of Δ0α+γ-measurable Q-valued functions is isomorphic to the Δ0β-degrees of Δ0β+γ-measurable Q-valued functions, and these are isomorphic to the generalized homomorphism order on the γ-th iterated Q-labeled forests.
KW - better quasiorder
KW - Borel hierarchy
KW - Wadge degree
UR - http://www.scopus.com/inward/record.url?scp=85133334471&partnerID=8YFLogxK
U2 - 10.1090/proc/15930
DO - 10.1090/proc/15930
M3 - Article
AN - SCOPUS:85133334471
VL - 150
SP - 3989
EP - 4003
JO - Proceedings of the American Mathematical Society
JF - Proceedings of the American Mathematical Society
SN - 0002-9939
IS - 9
ER -
ID: 126984597