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20220711 19:50:34 +0200  answered a question  Color nodes of poset The solution is to build the poset with an explicit "facade = True", even though this should have been the default. I st 
20220711 19:38:25 +0200  commented question  Color nodes of poset possibly related: although "alpha[4] in Q" is True, "alpha[4] in list(Q)" is apparently False. I think this must be a bu 
20220711 19:35:26 +0200  asked a question  Color nodes of poset Color nodes of poset I have a poset Q and an element alpha[4] of Q. If I type "alpha[4] in Q", Sage correctly responds " 
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20130613 17:16:51 +0200  marked best answer  referencing polynomial variables Note that it is also possible to do this in a genuine 
20130526 19:10:50 +0200  answered a question  referencing polynomial variables The simplest solution is just to use dictionary arguments for subs. Instead of which throws a SyntaxError, you can write 
20130403 19:12:04 +0200  asked a question  referencing polynomial variables Suppose I have a polynomial $f$ in the variables $x_1, \dots, x_5$ defined by something like where mylist is some list of integers. Then I can evaluate $f$ by e.g. Question: How do I do this evaluation when $f$ is in $n>>0$ variables? I want to write something like but this isn't a valid argument for subs. This must be some way to coerce this to work. 
20121115 17:53:12 +0200  answered a question  combinat install The solution was to reinstall sage from source. 
20121115 17:52:12 +0200  commented question  combinat install Thank you! I reinstalled from source, and now combinat will work for me. 
20121114 15:28:16 +0200  commented question  combinat install oliver@puter:~$ sage b main  sage: Building and installing modified Sage library files. Installing c_lib g++ o libcsage.so shared src/convert.os src/interrupt.os src/memory.os src/mpn_pylong.os src/mpz_pylong.os src/mpz_longlong.os src/stdsage.os src/gmp_globals.os src/ZZ_pylong.os src/ntl_wrap.os L/home/oliver/sage5.4linux32bitubuntu_12.04.1_ltsi686Linux/local/lib L/home/oliver/sage5.4linux32bitubuntu_12.04.1_ltsi686Linux/local/lib/python2.7/config lntl lpari lgmp lpython2.7 /usr/bin/ld: cannot find crti.o: No such file or directory collect2: ld returned 1 exit status scons: *** [libcsage.so] Error 1 Error building c_lib. 
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20121112 17:09:43 +0200  commented question  combinat install The reinstallation of sage is fine, but I am scared to try combinat again without knowing what went wrong the first time. 
20121112 12:29:52 +0200  asked a question  combinat install I was running sage 5.3 on a lubuntu 12.04 machine. Everything was fine. Then I tried
Now when I try to use sage, it says
Is this a known issue? I am currently reinstalling sage 5.4 and hoping that it will work this time. Please advise. Thanks! UPDATE: I tried it again in 5.4 and got the following error:

20121108 12:39:33 +0200  commented answer  Skew commuting variables Thanks! This is exactly what I needed! 
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20121108 12:39:13 +0200  marked best answer  Skew commuting variables You can use our wrapper for Singular's noncommutative component Plural. In particular, you can create a Galgebra for this ring as follows: 
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20121107 18:22:17 +0200  asked a question  Skew commuting variables I want to work in the ring I seems like FreeAlgebraQuotient is the thing to use, but I am not sure how. In the documentation for FreeAlgebraQuotient, the algebras are 4dimensional as modules over QQ. However in my application, the algebra is infinitedimensional as a module, so I can't write down the matrices for the action of the generators. Is there another way to obtain this ring? Thanks. 