<div class='user_solution'>1.Kxc7?  [2.Sxb6#]<div>1...e5  2.g8=Q#</div><div>1...Qb1  2.Rxd4#</div><div>1...Rxf4  2.Sxf4#</div><div>1...Rxc4! <b>a</b></div><div>1...Qxc4! <b>b</b></div><div><br /></div><div>1.Qa8?  [Rxc7#]</div><div>1...Rxc4 <b>a</b>  2.Rc5# <b>A</b></div><div>1...Qxc4!</div><div><br /></div><div>1.dxc7?  [2.Sxb6#]</div><div>1...Rxc4 <b>a</b>  2.Rd6# <b>B</b></div><div>1...Qb1  2.Rxd4#</div><div>1...Rxf4  2.Sxf4#</div><div>1...Qxc4! <b>b</b></div><div><b><br /></b></div><div>1.Qb1?  [2.Qb5#]</div><div><u>1...Qxc4 <b>b</b>  2.Qe4# </u><b><u>D</u><font size="4" color="#ff0000">*</font></b></div><div>1...Qxb1  2.Rxd4#</div><div>1...Rxc4! <b>a</b></div><div><br /></div><div><b>1.Qa2!</b>  [2.Sxb6#]</div><div>1...Rxc4 <b>a </b> 2.Qxc4# <b>C</b></div><div><u>1...Qxc4 </u><b style="text-decoration-line: underline;">b</b><u>  2.Rxd4# </u><b><u>E</u><font size="4" color="#ff0000">**</font></b></div><div>1...Rxf4  2.Sxf4# </div><div><br /></div><div>- Interchange of functions between two units: A and B after the same defence. In a try the piece A pins and piece B mats. In actual play piece B pins and piece A mats.</div><div><br /></div><div>(<font size="4" color="#ff0000"><b>*</b></font>The checkmate is possible because bRd4 is pinned by the Rook</div><div><font size="4" color="#ff0000"><b>**</b></font>The checkmate is possible because bQc4 is pinned by the Queen)</div><div>See in next article in <i>&quot;Problemas&quot;</i>, magazine of October 2020, with more examples.</div><div><br /></div><div>- Kharkov 1</div><div>- Double Kharkov 2</div><br /></div>