List of Papers
*For accepted or published article, the latest version on arXiv is equivalent to the published version [possibly up to typos and styles].

*Since 2017, I stopped submitting to Elsevier Journals.

[1]Haagerup property for C*-algebras and rigidity of C*-algebras with property (T)
J. Funct. Anal. 265 (2013), 1778--1799. doi:10.1016/j.jfa.2013.06.007, arXiv:1212.5030
[2]Amenable minimal Cantor systems of free groups arising from diagonal actions
J. reine angew. Math. 722 (2017), 183--214. doi:10.1515/crelle-2014-0071, arXiv:1312.7098
[3](With M. Mimura, N. Ozawa, and H. Sako)Group approximation in Cayley topology and coarse geometry, Part III: Geometric property (T)
Algebr. Geom. Topol. 15 (2015), no.2, 1067--1091. doi:10.2140/agt.2015.15.1067, arXiv:1402.5105
[4]Group C*-algebras as decreasing intersection of nuclear C*-algebras
Amer. J. Math. 139 (2017), number 3, 681--705. doi:10.1353/ajm.2017.0018, arXiv:1410.8347(Original version is available here.)
[5]Construction of minimal skew products of amenable minimal dynamical systems
Groups Geom. Dyn. 11 (2017), 75--94. doi:10.4171/GGD/388 arXiv:1503.01317
[6]Minimal ambient nuclear C*-algebras
Adv. Math. 304 (2017), 421--433. doi:10.1016/j.aim.2016.09.002, arXiv:1510.05592
[7]Elementary constructions of non-discrete C*-simple groups
Proc. Amer. Math. Soc. 145 (2017), 1369--1371. doi:10.1090/proc/13301, arXiv:1604.03032
Comment:This article provides the first examples of non-discrete C*-simple groups, answering de la Harpe's question.
[8]Almost finiteness for general etale groupoids and its applications to stable rank of crossed products
Int. Math. Res. Not., 2020 (2020), 6007--6041, doi:10.1093/imrn/rny187, arXiv:1702.04875
[9]Simple equivariant C*-algebras whose full and reduced crossed products coincide
J. Noncommut. Geom. 13 (2019), 1577--1585, doi:10.4171/JNCG/356 arXiv:1801.06949
[10]Complete descriptions of intermediate operator algebras by intermediate extensions of dynamical systems
Commun. Math. Phys. 375 (2020), 1273--1297, doi:10.1007/s00220-019-03436-1, online free view, arXiv:1805.02077
Citation omission: The Main Theorem in the W*-case has been obtained by Packer
under the additional assumption on the existence of normal conditional expectations, by a different von Neumann algebraic method.
[11]Rigid sides of approximately finite dimensional simple operator algebras in non-separable category
Int. Math. Res. Not.  2021 (2021), 2166--2190, doi:10.1093/imrn/rnz079, arXiv:1809.08810
Typo: Prop 2.4 (2), "countably generated" -> "countably decomposable".
[12]The approximation property and exactness of locally compact groups
J. Math. Soc. Japan 73 Number 1 (2021), 263-275, doi:10.2969/jmsj/83368336, arXiv:1901.07430
[13]On pathological properties of fixed point algebras in Kirchberg algebras
Proc. Roy. Soc. Edinburgh Section A: Mathematics 150, Issue 6 (2020), 3087--3096, doi:10.1017/prm.2019.47, arXiv:1905.13004
Remark:Numbers (A, B, C) of theorem etc. are deleted in the published version due to the style of the publisher.
[14]Non-amenable tight squeezes by Kirchberg algebras
Math. Ann. 382 (2022), 631--653, doi:10.1007/s00208-021-02262-y, online free view, arXiv:1908.02971
[15]Equivariant O_2-absorption theorem for exact groups
Compos. Math. 157 (2021), Volume 7, 1492--1506, doi:10.1112/S0010437X21007168, arXiv:2004.09461
A slide on this work.
[16](With N. Ozawa)On characterizations of amenable C*-dynamical systems and new examples
Selecta Math.(N.S.) 27 (2021), Article number 92, 29pp, doi:10.1007/s00029-021-00699-2[open access], arXiv:2011.03420
-Correction in Proposition 3.5(06 Feb.2022): replace S(A) with Q(A) \setminus {0} in the non-unital case.
-Comment: Actually, the equivalence "amenability <=> QAP" is a new result of this paper even for discrete groups,
as the referred article contained a fatal error, and the authors of that article retracted the original statement.
Note that our proof is independent from the said work, hence is not affected by their errors.

[17]C*-simplicity has no local obstruction
Forum Math. Sigma 10  (2022) e18, 8 pages, doi:10.1017/fms.2022.5[open access], arXiv:2103.10404
A slide on this work.
[18]Simplicity and tracial weights on non-unital reduced crossed products
Internat. J. Math. 35, no.6 (2024), 16 pages, doi:10.1142/S0129167X24500216, arXiv:2109.08606
A short slide on this work.

[19]Every countable group admits amenable actions on stably finite simple C*-algebras
Amer. J. Math. 148 no.1 (2026), 69--77,  doi:10.1353/ajm.2026.a980768 arXiv:2204.04480
[20]Amenable actions on finite simple C*-algebras arising from flows on Pimsner algebras
To appear in Muenster J. Math., special issue in honour of Eberhard Kirchberg (invited), arXiv:2305.13056
-Correction in the proof of 5.5(4 Oct.2026, indicated by Mukohara):
The argument using [36] 4.14 was not justified as it was not clear if the sequences can be chosen to be positive,
but can be justified by using tracial proper outerness introduced and studied in our article arXiv:2605.21128.
[21]Amenable actions on ill-behaved simple C*-algebras
Int. Math. Res. Not. 2025 , no.5, 18 pages, doi:10.1093/imrn/rnaf033, arXiv:2405.10191
[22]Crossed product splitting of intermediate operator algebras via 2-cocycles
Math. Ann. 394 (2026), article number 38, doi:10.1007/s00208-026-03314-x, arXiv:2406.00304
-Correction (4 Oct.2026): Remove Remark 5.1 as it only holds true for discrete groups (this does not affect any other parts of the paper).
[--](With M. Mukohara)Stabilization theorem and symmetric structure of Cuntz-Pimsner algebras
Preprint, arXiv:2605.21128
Comment: In revision v3, we give a very short solution
to the reduced Hao--Ng isomorphism problem for C*-dynamics in full generality,
and disprove the full Hao--Ng conjecture by constructing explicit counerexamples, which also settle several questions in the literature.
Surprisingly, despite decades of research, both proofs are significantly simple and less than a page long!
Note: After sending our v3 to Dor-On and I. Thompson (Aug. 31, 08:52 UTC),
we are informed by them that they independently obtained counterexamples to the full conjecture by a different approach.
[--]Free groups amenably act on unital simple AF-algebras
Preprint, arXiv:2610.01460





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