<div class="user_solution"><span style="line-height: 107%;">* 1. ... Kh2 <font face="Times New Roman, serif"><span style="font-size: 12pt;">[a] 2. Se5 </span></font></span><span style="line-height: 107%;">[</span><span style="line-height: 107%;"><span style="line-height: 107%;">A</span>]</span><span style="line-height: 107%;"> Rh1? 3. Sxf3#</span><span style="line-height: 107%;"><br /></span></div><div class="user_solution"><span style="line-height: 107%;"></span><span style="line-height: 107%;">2. ... Kh1/gxf2 </span><span style="line-height: 107%;"><span style="line-height: 107%;" lang="EN-US"> </span>3. Sg4(+) </span><span style="line-height: 107%;">gxf2/Kh1 4. Sxf2+ Kh2 5. Sg4+ Kh1 6. Kg3 f2 7. Sxf2#</span><span style="line-height: 107%;"><br /></span></div><div class="user_solution"><span style="line-height: 107%;"><span style="line-height: 107%;">* </span>1. ... gxf2 [b] 2. Sxf2+ </span><span style="line-height: 107%;"><span style="line-height: 107%;" lang="EN-US"><span style="line-height: 107%;">[C</span><span style="line-height: 107%;">]</span> </span>Kh2 </span><span style="line-height: 107%;"><span style="line-height: 107%;">[a] </span>3. Sg4+ </span><span style="line-height: 107%;"><span style="line-height: 107%;">[</span><span style="line-height: 107%;"><span style="line-height: 107%;">B</span>] </span>Kh1 4. Kg3 f2 5. Sxf2#</span></div><div class="user_solution"><span style="line-height: 107%;"><br /></span></div><div class="user_solution"><span style="line-height: 107%;">1. Se5? </span><span style="line-height: 107%;">Kh2 </span><span style="line-height: 107%;">[a]</span><span style="line-height: 107%;"> 2. Sg4+ [</span><span style="line-height: 107%;"><span style="line-height: 107%;">B</span>] Kh1 3. Kh5! gxf2 4. Sxf2+ Kh2 5. Kh4 Rh1 6. </span><span style="line-height: 107%;" lang="EN-US">Sg4+ Kg1 7. Bf2#</span><span style="line-height: 107%;" lang="EN-US"> MM<br /></span></div><div class="user_solution"><div class="user_solution"><span style="line-height: 107%;" lang="EN-US">1. ... gxf2!</span><span style="line-height: 107%;" lang="EN-US"> </span><span style="line-height: 107%;" lang="EN-US"><span style="line-height: 107%;">[</span></span><span style="line-height: 107%;" lang="EN-US"><span style="line-height: 107%;"><span style="line-height: 107%;" lang="EN-US"><span style="line-height: 107%;"></span>b</span>]</span><br /></span></div><span style="line-height: 107%;"></span></div><div class="user_solution"><span style="line-height: 107%;"></span><span style="line-height: 107%;" lang="EN-US">1. Kg4/Kh5? gxf2 </span><span style="line-height: 107%;" lang="EN-US"><span style="line-height: 107%;">[</span></span><span style="line-height: 107%;" lang="EN-US"><span style="line-height: 107%;"><span style="line-height: 107%;" lang="EN-US"><span style="line-height: 107%;"></span>b</span>]</span> 2. Sxf2+ </span><span style="line-height: 107%;" lang="EN-US"><span style="line-height: 107%;" lang="EN-US"><span style="line-height: 107%;">[C</span><span style="line-height: 107%;">]</span> </span>Kh2 </span><span style="line-height: 107%;" lang="EN-US"><span style="line-height: 107%;"><span style="line-height: 107%;">[a] </span></span>3. </span><span style="line-height: 107%;">Kh4 </span><span style="line-height: 107%;"><span style="line-height: 107%;">[</span><span style="line-height: 107%;"><span style="line-height: 107%;">D</span>] </span>Rh1 4. Sg4+ Kg1 5. Bf2#</span></div><div class="user_solution"><span style="line-height: 107%;" lang="EN-US">1. ... Kh2! </span><span style="line-height: 107%;">[a]</span><span style="line-height: 107%;" lang="EN-US"></span></div><div class="user_solution"><b><span style="line-height: 107%;" lang="EN-US"><br /></span></b></div><div class="user_solution"><span style="line-height: 107%;" lang="EN-US"><b>1. fxg3!</b> Kh2? </span><span style="line-height: 107%;" lang="EN-US"><span style="line-height: 107%;">[a]</span> 2. Sf2 </span><span style="line-height: 107%;" lang="EN-US"><span style="line-height: 107%;">[C</span><span style="line-height: 107%;">]</span> Rh1 3. Sg4+ Kg1 4. Bf2#</span><span style="line-height: 107%;" lang="EN-US"><br /></span></div><div class="user_solution"><span style="line-height: 107%;" lang="EN-US">1. ... f2 2. Sxf2+ Kh2 3. Sd3? Kh1 4. g4 Kh2 5. Bg3+ Kh1 6. Sf2#</span></div><div class="user_solution"><span style="line-height: 107%;" lang="EN-US">3. ... Rh1!<br /></span></div><div class="user_solution"><span style="line-height: 107%;" lang="EN-US">3. </span><span style="line-height: 107%;">Sg4+ Kh1 4. Se5 Kh2 5. g4 Rh1? 6. </span><span style="line-height: 107%;" lang="NL">Sf3#</span><span style="line-height: 107%;"><br /></span></div><div class="user_solution"><span style="line-height: 107%;">5. ... Kh1 6. Sd3 Kh2 7. Bg3+ Kh1 8. </span><span style="line-height: 107%;" lang="EN-US">Sf2#</span><span style="line-height: 107%;" lang="EN-US"> </span><span style="line-height: 107%;" lang="EN-US"><span style="line-height: 107%;" lang="EN-US">M</span></span><span style="line-height: 107%;" lang="EN-US"><span style="line-height: 107%;" lang="EN-US">M</span></span></div><div class="user_solution"><span style="line-height: 107%;" lang="EN-US"><br /></span></div><div class="user_solution"><span style="line-height: 107%;" lang="EN-US">Keywords: White to play, complete block, capture key, pure round trip (S), switchback (Sk,KSk,Sk), pendulum (k), changed continuations (3-phase: aAaBaC, 2-phase: bCaBbCaD), changed mates, mate on same square, model mates, annihilation, sacrifice of black piece (active), square vacation, selfblock, line opening (e1-g3,f3-f2), tempo move (K), corner mate, interchange in mating position (kr (2))<br /></span><div> <span style="line-height: 107%;" lang="EN-US"> </span></div><span style="line-height: 107%;" lang="EN-US"></span></div><br />