▁Anders sen ▁for ▁the ▁world ▁championship . ▁The ▁eight - game ▁match ▁was ▁a ▁tie ▁and ▁Anders sen ▁remained ▁an ▁uno fficial ▁world ▁champion . ▁ ▁Paul sen ▁defeated ▁Anders sen ▁in ▁matches ▁in ▁ 1 8 7 6 ▁and ▁ 1 8 7 7 . ▁ ▁Paul sen ▁has ▁many ▁contributions ▁in ▁the ▁opening ▁theory ▁such ▁as ▁the ▁Sic ilian ▁Dragon , ▁the ▁Sic ilian ▁Paul sen ▁Vari ation , ▁French ▁Def ense ▁Paul sen ▁Att ack ▁and ▁Vienna ▁Game ▁Paul sen ▁Vari ation . ▁ ▁He ▁played ▁in ▁the ▁final ▁match ▁of ▁the ▁ 1 8 5 7 ▁First ▁American ▁Ch ess ▁Congress , ▁losing ▁to ▁Paul ▁Mor phy ▁five ▁games ▁to ▁one ▁with ▁two ▁draw s . ▁ ▁Paul sen ▁pa wn s ▁ ▁Paul sen ▁pa wn s ▁is ▁a ▁term ▁co ined ▁by ▁N im z ow itsch ▁for ▁a ▁restricted ▁ ▁with ▁two ▁pa wn s ▁on ▁squares ▁d 6 ▁and ▁e 6 ▁for ▁Black ▁or ▁d 3 ▁and ▁e 3 ▁for ▁White , ▁often ▁couple d ▁with ▁an ▁open ▁c -. ▁This ▁restricted ▁centre ▁makes ▁it ▁difficult ▁for ▁the ▁oppon ent ▁to ▁wh ip ▁up ▁a ▁quick ▁attack ▁by ▁adv ancing ▁his ▁centre . ▁Paul sen ▁pa wn s ▁are ▁the ▁stal wart ▁of ▁the ▁Paul sen ▁Vari ation ▁of ▁the ▁Sic ilian ▁Def ence . ▁ ▁Ch ess ▁opening ▁contributions ▁ ▁Sic ilian ▁Dragon ▁ ▁The ▁modern ▁form ▁of ▁the ▁Dragon ▁was ▁origin ated ▁by ▁Paul sen ▁around ▁ 1 8 8 0 . ▁It