????:1???????????:?????

2??????????

3????????

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

5?300??????

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

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

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

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

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

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