Length function: Difference between revisions

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Removed essay tag, did not seem appropriate in this case.
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==Properties==
A group with a length function does ''not'' form a [[filtered group]], meaning that the [[sublevel set]]s <math>S_i := \{g \mid l\ell(g) \leq i\}</math> do not form subgroups in general.
 
However, the [[group ring|group algebra]] of a group with a length functions forms a [[filtered algebra]]: the axiom <math>l\ell(gh) \leq l\ell(g)+l\ell(h)</math> corresponds to the filtration axiom.
 
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