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Excelsior (chess problem)
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<h2 id="backstory">Backstory</h2> <p>Loyd had a friend who was willing to wager that he could always find the piece which delivered the principal mate of a chess problem. Loyd composed this problem as a joke and bet his friend dinner that he could not pick a piece that <i>didn't</i> give mate in the main line (his friend immediately identified the pawn on b2 as being the least likely to deliver mate), and when the problem was published it was with the stipulation that White mates with "the least likely piece or pawn".<a class="footnote-ref" id="fnref:2" href="#fn:2"><sup>2</sup></a> Its first publication, in 1861, is not accompanied by any such stipulation.<a class="footnote-ref" id="fnref:3" href="#fn:3"><sup>3</sup></a> </p> <h2 id="solution">Solution</h2> <p>1. b4! </p> Threatening 2.Rf5 <i>any</i><a class="footnote-ref" id="fnref:4" href="#fn:4"><sup>4</sup></a> 3.Rf1# or 2.Rd5 <i>any</i> 3.Rd1# (with possible prolonging of both by 2...Rc5 3.bxc5 <i>any</i> 4.R mates). White cannot begin with 1.Rf5 because Black's 1...Rc5 would pin the rook. Now there are multiple possible moves defending only one of the threats and one secondary non-thematical defence: 1...Rxc2 2.Nxc2! a2 3.Rd5 (or Rf5) a1=Q 4.Nxa1 <i>any</i> 5.R mates. <p>1... Rc5+ 2. bxc5! </p> Threatening 3.Rb1#. <p>2... a2 3. c6! </p> Again with the same threats as on move one, i.e. 4.Rf5 <i>any</i> 5.Rf1# or 4.Rd5 <i>any</i> 5.Rd1#. <p>3... Bc7 </p> Because both Rd5 and Rf5 are threatened; the alternative moves 3...Bf6 and 3...Bg5 would only defend against one or the other. The given move does defend against Rd5 in the sense that 4.Rd5 Bxg3 5.Rd1+ Be1 6.Rdxe1# takes more than the required five moves, and similarly for 4.Rf5 Bf4. <p>4. cxb7 <i>any</i> 5. bxa8=Q/B# </p> The mate is delivered with the pawn that starts on b2. <p>Any problem that features a pawn moving from its starting square to promotion in the course of the solution is now said to demonstrate the <i>Excelsior</i> theme. Nowadays it is most usually shown in <a href="/facts/Helpmate/8VP7thnj">helpmates</a> and <a href="/facts/Seriesmover/nWP8KThW">seriesmovers</a>. </p> <h2 id="notes">Notes</h2> <h2 id="references">References</h2> <ol> <li id="fn:1"><p>"Vladimir Korolkov | Russian chess composer | Britannica". www.britannica.com. Retrieved 2022-11-08. <a href="https://www.britannica.com/biography/Vladimir-Korolkov" target="_blank">https://www.britannica.com/biography/Vladimir-Korolkov</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li> <li id="fn:2"><p>Sam Loyd and His Chess Problems - Alain C. White (p396 in Dover 1962 reprint). White quotes a letter from Loyd stating that the "friend" was Dennis Julien, and the problem was composed in 1858. <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li> <li id="fn:3"><p>"Chess column". The Era. XXIII (1164): 15. January 13, 1861. <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li> <li id="fn:4"><p>Any legal move by Black. <a href="#fnref:4" class="footnote-back-ref">↩</a></p></li> </ol>