±Û¾´ÀÌ: dskim (dskim)
³¯ Â¥: Tue Mar 24 04:47:13 1998
Á¦ ¸ñ: Re^3: À¥ÆäÀÌÁö¿¡¼­... Áú¹®ÀÔ´Ï´Ù.

mengpa> (1) ¸ÕÀú, `qfactor` procedureÀÇ ³»¿ë°ú, ±× °á°úÀÇ Àǹ̸¦
mengpa> ¸ð¸£°Ú½À´Ï´Ù.

> sort(add(numbpart(n)*q^n,n=0..100),q);
> qfactor(",100);

mengpa> ÀÇ °á°ú´Â ...

mengpa> 1,[1, -1],[2, -1],[3, -1],[4, -1], ..., [100, -1] ÀÔ´Ï´Ù¸¸...

[a,n] means a factor (1-q^a)^n. The first 1 means the leading term is 1.

mengpa> ¿ø·¡ÀÇ Generating FunctionÀ¸·ÎºÎÅÍ ¾î¶² Á¤º¸¸¦ ¾òÀ¸·Á´Â °ÍÀÎÁö
mengpa> ±Ã±ÝÇÕ´Ï´Ù. (qfactorÀÇ source code´Â ¿­½ÉÈ÷ ÇØ¼®Çغ¸°í ÀÖ´Â
mengpa> ÁßÀÔ´Ï´Ù. ^_^;)

We are trying to express the generating function as a product of factors
(1-q^a).

mengpa> (2) ±× ´ÙÀ½¿¡ ¼Ò°³ÇϽЏí·É,

mengpa> # ´ÙÀ½ »ý¼ºÇÔ¼ö°¡ partµé »çÀÌÀÇ Â÷°¡ 2 ÀÌ»óÀÎ ÀÚ¿¬¼ö ºÐÇÒÀÇ °³¼ö¸¦
mengpa> ¼Á´Ï´Ù.

> taylor(add(q^(i^2)/aqn(q,q,i),i=0..100),q,100);
> qfactor(",100);

mengpa> ¿¡¼­ 'taylor' ÇÔ¼ö¸¦ ¾´ ÀÌÀ¯¸¦ ¸ð¸£°Ú½À´Ï´Ù.

'taylor' computes the coefficients of the powers of q^n.

mengpa> ù° ÁÙ (`taylor`°¡ ÀÖ´Â)À» ½ÇÇàÇÑ °á°ú¸¦ ºÁ¼­ µ¹¾Æ°¡´Â °Ç
mengpa> ¾Ë°Ú´Âµ¥, ±× ¹Ø¿¡¼­ ½ÇÇàÇÑ `qfactor`ÀÇ °á°ú´Â ¾î¶»°Ô ÇØ¼®Çؾß
mengpa> ÇÏ´ÂÁö¿ä...

It is not apparent why it factors into that form. We can easily interpret
the factors, but the equality is not apparent.

mengpa> (3) À̰Ç, ±×³É ±Ã±ÝÇØ¼­Àε¥, ±³¼ö´Ô²²¼­´Â `aqn` procedure¸¦ ½á¼­
mengpa> q-analog·Î generating functionÀ» ¸¸µå¼Ì´Âµ¥(¸Â´Â ¾ê±ä°¡¿ä?)
mengpa> ¾ÆÁ÷ °¨ÀÌ Á¦´ë·Î ¿ÀÁö ¾Ê´Â±º¿ä.

aqn is a kind of q-analogue of a factorial. aqn(q,q,n)=(1-q)...(1-q^n).
aqn(q,q,n)/(1-q)^n -> n! as q -> 1.

mengpa> ÀϹÝÀûÀÎ(½±°í ¿ø½ÃÀûÀÎ) generating functionÀ» Á¤ÀÇÇÏ°í ½Í¾î¼­
mengpa> help¸¦ µÚÁ³´Âµ¥, rgf_... ½ÄÀÇ ÇÔ¼öµéÀÌ genfunc package¿¡ ÀÖ´õ±º¿ä.
mengpa> À̵éÀÇ »ç¿ë¹ýÀ» ¼Ò°³ÇØ ÁÖ½Ç ¼ö ÀÖÀ¸½Ç·±Áö¿ä...

I will explain this later.

Good luck!

dskim

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