# IRC log for #cdk, 2009-05-18

All times shown according to UTC.

Time Nick Message
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11:07 egonw ok, let's assume the first structure
11:07 egonw (since this is CDK related, better on this channel)
11:07 egonw the partitioning would be:
11:07 maclean indeed
11:08 egonw 4,3,1,1,1 ?
11:08 egonw no, that does not sum up
11:08 egonw mmm...
11:08 egonw how do you get to 10 for 4 carbons again?
11:09 maclean see the next blog post :)
11:09 egonw ok :)
11:09 maclean 4 * 4 - 6 = 10
11:09 egonw UIT must be circumvented in any case
11:09 egonw those partitionings with val>4 are easy not to create
11:09 egonw ok
11:09 maclean ie : (carbon valence) * (number of carbons) - (number of hydrogens) = N
11:09 egonw so, for C5H10:
11:10 maclean 20 - 10 = 10
11:10 egonw 5*4 - 10 = 10 too
11:10 maclean indeed
11:10 egonw ok, so 4,3,1,1,1 does sum up
11:10 egonw and the second one would be:
11:10 maclean <10, 5> = [[6, 1, 1, 1, 1], [5, 2, 1, 1, 1], [4, 3, 1, 1, 1], [4, 2, 2, 1, 1], [3, 3, 2, 1, 1], [3, 2, 2, 2, 1], [2, 2, 2, 2, 2]]
11:10 egonw 4,2,2,1,1 ?
11:11 maclean what, the dimethyl cyclopropane?
11:11 egonw maclean: yes
11:11 maclean yes
11:11 egonw it is possible to calculate the gain with this approach?
11:11 maclean probably
11:11 egonw compared trying all structures?
11:11 maclean hmmm.
11:12 maclean there are ways to calculate the O(fn) for recursive procedures.
11:12 maclean I may not have the maths, though.
11:12 egonw yes, I understand
11:12 egonw (neither do I)
11:12 maclean but, I should say, that I can make C6H12, which I could not have even tried before
11:13 egonw btw, the above expansion <10, 5> = should not be difficult to rewrite as:
11:13 egonw <10,5,4>
11:13 maclean I gave up on C7H14 halfway...
11:13 egonw but then again...
11:13 egonw other nuclei is a more stringent problem
11:13 egonw what you need instead is:
11:13 egonw <10,{4,4,4,4}>
11:14 egonw but not quite that either
11:14 maclean I don't know of an algorithm for generating P(m, n, o), only P(m, n), but it is trivial to throw away partitions with valencies that are too high.
11:14 egonw well, looking forward to your future blogs
11:15 maclean wait, take a look at this code snippet (you don't have to understand it :)
11:16 maclean http://gist.github.com/113422
11:16 maclean that's the python to make partitions from <m, n>
11:16 maclean :)
11:16 maclean (it's almost identical to the pseudocode in the book I used)
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13:32 sneumann
13:34 maclean
13:35 sneumann focus in the wrong window ;-)
13:42 maclean :)
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