▁ ▁It ▁leads ▁to ▁a ▁series ▁of ▁Se i berg ▁dual ities ▁known ▁as ▁a ▁du ality ▁cas cade . ▁ ▁It ▁was ▁introduced ▁by ▁Matthew ▁Str ass ler ▁and ▁Ig or ▁Kle ban ov ▁in ▁Super gravity ▁and ▁a ▁Conf ining ▁G au ge ▁Theory : ▁D ual ity ▁C asc ades ▁and ▁S B - Resol ution ▁of ▁N aked ▁Sing ular ities . ▁ ▁It ▁is ▁not ▁known ▁whether ▁Se i berg ▁du ality ▁exists ▁in ▁ 3 - dimensional ▁non abel ian ▁gauge ▁theories ▁with ▁only ▁ 4 ▁super charg es , ▁although ▁a ▁conject ure ▁has ▁appeared ▁in ▁Fra ction al ▁M 2 - b ran es ▁in ▁some ▁special ▁cases ▁with ▁Ch ern – Sim ons ▁terms . ▁ ▁References ▁ ▁Electric - Mag net ic ▁D ual ity ▁in ▁Sup ers ym metric ▁Non - Ab elian ▁G au ge ▁The ories ▁by ▁Nathan ▁Se i berg . ▁ ▁Category : Quant um ▁field ▁theory ▁Category : S up ers ym met ry ▁Category : Quant um ▁chrom od ynam ics ▁Category : D ual ity ▁theories <0x0A> </s> ▁Rafael ▁Nad al ▁was ▁the ▁def ending ▁champion ▁and ▁successfully ▁def ended ▁his ▁title , ▁defeated ▁long - time ▁rival ▁Roger ▁Feder er ▁▁▁▁ ▁to ▁win ▁the ▁Men ' s ▁Singles ▁tennis ▁title ▁at ▁the ▁ 2 0 1 1 ▁French ▁Open , ▁t ying ▁him ▁with ▁B jör n ▁Borg ▁for ▁most ▁in ▁the ▁Open ▁Era . ▁It ▁was ▁the ▁fourth ▁time ▁Nad al ▁had ▁defeated