Abstract
For several natural filtrations of a free group S, we express the n-th term of the filtration as the intersection of all kernels of homomorphisms from S to certain groups of upper-triangular unipotent matrices. This generalizes a classical result of Grün for the lower central filtration. In particular, we do this for the n-th term in the lower p-central filtration of S.
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This work was supported by the Israel Science Foundation (Grant No. 152/13).
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Efrat, I. Filtrations of free groups as intersections. Arch. Math. 103, 411–420 (2014). https://doi.org/10.1007/s00013-014-0701-x
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DOI: https://doi.org/10.1007/s00013-014-0701-x