Talk:Ordered partitions: Difference between revisions
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:: to make it clearer --[[User:Newgame|Eugen]] 10:36, 8 February 2011 (UTC) |
:: to make it clearer --[[User:Newgame|Eugen]] 10:36, 8 February 2011 (UTC) |
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::: Oh! No, the original page was right, and I was wrong, about that left vs. right thing with the word "choose". |
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::: My problems were twofold: First, I did not have a definition of "choose", and second I did not know how to group operations when faced with a + b choose c. I went with a + (b choose c), but it's now clear to me that I should have gone with (a+b) choose c. The current main page shows operator precedence clearly, but still could do with a link to a definition. (The link to [[Combinations]] suggests a definition, and there can be good reasons to order the arguments that way, but that does not actually define the operation the original (anonymous) author intended for [http://mathworld.wolfram.com/Combination.html<code>choose</code>]. Perhaps the right approach here would be to mention popular notation issues on the [[Combinations]] page?) --[[User:Rdm|Rdm]] 15:55, 8 February 2011 (UTC) |
Revision as of 15:55, 8 February 2011
Incorrect math statement
The task says:
- Note that the number of elements in the list is
But this cannot be right.
The task with args 1,2,4 would generate 105 distinct partitions. But 4 choose 1
is 0 and 4 choose 2
is 0 and 4 choose 4
is 1, so the above formula would give a result of 6. --Rdm 22:27, 7 February 2011 (UTC)
- Never mind, I fixed it. --Rdm 22:36, 7 February 2011 (UTC)
- Is it really fixed? As far as I know choose, the bigger number should be on the left. Anyways, I'll change it to
- to make it clearer --Eugen 10:36, 8 February 2011 (UTC)
- Oh! No, the original page was right, and I was wrong, about that left vs. right thing with the word "choose".
- My problems were twofold: First, I did not have a definition of "choose", and second I did not know how to group operations when faced with a + b choose c. I went with a + (b choose c), but it's now clear to me that I should have gone with (a+b) choose c. The current main page shows operator precedence clearly, but still could do with a link to a definition. (The link to Combinations suggests a definition, and there can be good reasons to order the arguments that way, but that does not actually define the operation the original (anonymous) author intended for
choose
. Perhaps the right approach here would be to mention popular notation issues on the Combinations page?) --Rdm 15:55, 8 February 2011 (UTC)
- My problems were twofold: First, I did not have a definition of "choose", and second I did not know how to group operations when faced with a + b choose c. I went with a + (b choose c), but it's now clear to me that I should have gone with (a+b) choose c. The current main page shows operator precedence clearly, but still could do with a link to a definition. (The link to Combinations suggests a definition, and there can be good reasons to order the arguments that way, but that does not actually define the operation the original (anonymous) author intended for