Geometric group theory and hyperbolic geometry

在与Papasoglu的合作中，Fujiwara建立了一个“JSJ-分解”的理论，该理论适用于沿着细长子群的群。这个结果是Rips-Sela关于沿沿着循环子群的JSJ-分解定理的一个推广，如果一个群的所有子群都是循环生成的，则称该群为“细长群”.例如，任何n阶生成的阿贝尔群和幂零群都是细长群，而秩至少为2的自由群不是细长群。该作品于2006年出版。

In a joint work with Papasoglu, Fujiwara established a theory of "JSJ-decomposition" for finitely presented group along slender subgroups. The result is a far reach generalization of the theorem by Rips-Sela on the JSJ-decomposition along cyclic subgroups.A group is said "slender" if all of its subgroups are finitely generated. For example, any finitely generated abelian groups and nilpotent groups are slender, while a free group of rank at least two is not slender. The work is published in 2006.