▁ 5 ... N x d 5 ▁as ▁" a ▁well - known ▁bad ▁move " ▁( or ▁words ▁to ▁that ▁effect ). ▁ ▁The ▁Fritz ▁Vari ation ▁ 5 ... N d 4 ▁and ▁Ul vest ad ' s ▁Vari ation ▁ 5 ... b 5 ▁are ▁related ▁as ▁they ▁share ▁a ▁common ▁sub vari ation . ▁American ▁master ▁O lav ▁Ul vest ad ▁introduced ▁ 5 ... b 5 ▁in ▁a ▁ 1 9 4 1 ▁article ▁in ▁Ch ess ▁Review . ▁White ▁has ▁only ▁one ▁good ▁reply : ▁ 6 . B f 1 !, ▁protect ing ▁g 2 ▁so ▁White ▁can ▁answer ▁ 6 ... Q x d 5 ▁with ▁ 7 . N c 3 . ▁Both ▁ 6 . B x b 5 ▁Q x d 5 ▁ 7 . B xc 6 ▁Q xc 6 ▁and ▁ 6 . dx c 6 ▁b xc 4 ▁ 7 . N c 3 ▁are ▁weak . ▁Black ' s ▁best ▁response ▁is ▁to ▁trans pose ▁to ▁the ▁Fritz ▁Vari ation ▁with ▁ 6 ... N d 4 , ▁making ▁another ▁advantage ▁of ▁ 6 . B f 1 ▁apparent — the ▁bishop ▁is ▁not ▁attacked ▁as ▁it ▁would ▁be ▁if ▁White ▁had ▁played ▁ 6 . Be 2 . ▁German ▁master ▁Alexander ▁Fritz ▁( 1 8 5 7 – 1 9 3 2 ) ▁suggested ▁ 5 ... N d 4 ▁to ▁Carl ▁Sch le chter , ▁who ▁wrote ▁about ▁the ▁idea ▁in ▁a ▁ 1 9 0