????:1???????:??50???????

2???????

3?400?4?????

4????????????

5????????

???????12?????????????????????21?????????? ???????:????????????20?????????????21?????????????,????5??????????,200??????

???????-??????????,??24???????,???????,??????????????,??????

?-?????????,?????????????????????,???,????,?????????????

????????????????,??????21?????????,??????2???????????5??????????????,????????????200??????,??????21???,?????40??

????,????????????50???????????,?Taleb A.,?????????????????????????,2006?????????

??????????,????????????????,???????20????,????

21??????????????????,?,????????????(?) ?????????????:?????