▁swift ▁turns . ▁ ▁Das ▁taught ▁in ▁this ▁rig orous ▁style ▁with ▁focus ▁on ▁t ay ari ▁( read iness ▁of ▁technique , ▁speed , ▁and ▁stam ina ) ▁and ▁lay k ari ▁( vir tu os ity ▁of ▁Indian ▁classical ▁rh yth mic ▁system ), ▁but ▁equally ▁emphas ises ▁k h ub sur ti ▁( be aut y ) ▁and ▁naz ak at ▁( del ic acy ▁and ▁ref in ement ). ▁ ▁Dan cers ▁must ▁become ▁ade pt ▁at ▁ab hin aya ▁( expression ) ▁and ▁learn ▁to ▁master fully ▁port ray ▁the ▁concept ▁of ▁' Ar d han aris w ara ' ▁( the ▁emb od iment ▁of ▁the ▁mascul ine ▁and ▁femin ine ) ▁in ▁their ▁dance . ▁ ▁Das ’ s ▁teaching ▁and ▁performance ▁also ▁emphas ise ▁Up aj , ▁or ▁impro vis ation . ▁ ▁Wh ilst ▁Das ▁has ▁ch ore ograph ed ▁many ▁group ▁pieces , ▁he ▁and ▁his ▁students ▁continue ▁to ▁present ▁traditional ▁full - length ▁Kath ak ▁sol os , ▁requiring ▁the ▁dan cer ▁to ▁improv ise ▁on ▁stage ▁with ▁live ▁mus icians ▁for ▁up ▁to ▁two ▁hours . ▁ ▁One ▁of ▁Das ' s ▁most ▁important ▁contributions ▁to ▁his ▁school ▁and ▁to ▁the ▁larger ▁field ▁of ▁Kath ak ▁is ▁his ▁development ▁of ▁" K ath ak ▁y oga ". ▁ ▁Kath ak ▁y oga ▁involves ▁the ▁practice ▁of ▁simultaneously ▁dan cing , ▁singing , ▁and ▁often , ▁playing ▁an ▁instrument . ▁ ▁In ▁Kath ak ▁y oga , ▁the ▁dan cer ▁rec ites