<div>b) 1.Nd1! (1.a5?)</div><div>1. ... Kg3 2.Kg1</div><div>(2.a5? Kh2 (2. ... Kf4? 3.Kg1 <span style="background: transparent;" id="solP1414161-59">transposes</span> <span style="background: transparent;" id="solP1414161-60">into</span> <span style="background: transparent;" id="solP1414161-61">main</span> <span style="background: transparent;" id="solP1414161-62">line!</span>)</div><div>3.Sf2 Kg3 4.Kg1 Kf4 5.Sd1 &amp; <span style="background: transparent;" id="solP1414161-75">two</span> <span style="background: transparent;" id="solP1414161-76">moves</span> <span style="background: transparent;" id="solP1414161-77">lost!</span>)<br /></div><div>2. ... Kf4 3.a5! Kg3 4.e3! dxe3 5.Nc3 threat 6.Ne2# MM</div><div><br /></div><div>Keywords: symbol problem (two united hearts), Forsberg twins, flight giving/taking key, active sacrifice of wPg3/e3, selfblock (bPg3/e3), tempo move (2./3. a5!), switchback (kf4-g3/e3-f4-g3/e3), model mate, square vacation (e1 at twin (a)).</div><div>Complete animation mode: https://pdb.dieschwalbe.de/P1414161.</div><br />