<div class='user_solution'>1.Sd7? Kxd7! <p style="margin: 0px; text-indent: 0px;">1.Qxd6? ed6! </p> <p style="margin: 0px; text-indent: 0px;"><br /></p> <p style="margin: 0px; text-indent: 0px;"> 1.Rf1!? Sc7! </p> <p style="margin: 0px; text-indent: 0px;"> 1.Rh2(3)!? Bc7! </p> <p style="margin: 0px; text-indent: 0px;"><br /></p> <p style="margin: 0px; text-indent: 0px;"> 1.O-O! (zz)  </p> <p style="margin: 0px; text-indent: 0px;"> 1...Bc7 2.Sd7! (zz) Kxd7 3.Rf8 (zz) B~ 4.Rd8# </p> <p style="margin: 0px; text-indent: 0px;"> 1...Sc7 2.Qxd6! ed6 3.Rc1 (zz) B~ 4.Rxc7#</p><p style="margin: 0px; text-indent: 0px;"><br /></p><p style="margin: 0px; text-indent: 0px;">Incarceration, Logical problem, Active sacrifice, Extended zugzwang </p></div>