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age | ||
visits | member for | 5 years, 4 months |
seen | Jun 19 at 7:49 | |
stats | profile views | 158 |
Mar
16 |
awarded | Nice Answer |
Mar
9 |
awarded | Nice Question |
Feb
17 |
awarded | Yearling |
Feb
17 |
accepted | Symplectic K-theory |
Feb
17 |
asked | Symplectic K-theory |
Apr
5 |
awarded | Popular Question |
Oct
29 |
accepted | Monoids and groups of fractions |
Oct
29 |
awarded | Scholar |
Oct
29 |
asked | Monoids and groups of fractions |
Nov
13 |
comment |
The free group $F_2$ has index 12 in SL(2,$\mathbb{Z}$)
If someone is still interested in an explicit homomorphism: there is one in Example 2.5 of these notes by Keith Conrads: math.uconn.edu/~kconrad/blurbs/grouptheory/SL(2,Z).pdf |
Apr
12 |
comment |
Rock-paper-scissors…
I guess "classification" is a soft term. For me, a classification is a one-to-one correspondence to a set of data together with a dictionary that allows you to just read off the answers to many interesting questions about the original objects, or at least answer them easily. In non-trivial cases, a classification will never enable you to answer all questions easily, so one has to specify "interesting questions". In this case "what is the number of instances of a given order?" should be one and if it's the only one, then classification in the sense above reduces to enumeration. |
Apr
11 |
awarded | Editor |
Apr
11 |
revised |
Rock-paper-scissors…
correction |
Apr
11 |
awarded | Supporter |
Apr
10 |
awarded | Nice Question |
Apr
10 |
awarded | Student |
Apr
10 |
asked | Rock-paper-scissors… |
Aug
29 |
answered | Is this the CAT(0) metric on an affine building? |
Jun
30 |
comment |
Properly Discontinuous Action
Of course, if a torsion-free group acts properly discontinuously, then it acts freely. So in that case the definitions are again equivalent. |
Jun
30 |
answered | Properly Discontinuous Action |