<?xml version="1.0" encoding="UTF-8" standalone="yes"?><oembed><version><![CDATA[1.0]]></version><provider_name><![CDATA[justpuzzles]]></provider_name><provider_url><![CDATA[https://justpuzzles.wordpress.com]]></provider_url><author_name><![CDATA[Teun Spaans]]></author_name><author_url><![CDATA[https://justpuzzles.wordpress.com/author/teunspaans/]]></author_url><title><![CDATA[Christmas 2017]]></title><type><![CDATA[link]]></type><html><![CDATA[<p>Dominosas are puzzles where the dominoes have been shuffled and turned face up. All the numbers are given, but the borders between the dominoes are not given &#8211; these have to be solved by the reader.<br />
I used to publish quarterly on them at my site <a href="https://spaanszt.home.xs4all.nl/Domino_Plaza.html#Puzzles">domino plaza</a>.</p>
<p>Usually a 6&#215;6 set of dominoes is used, though larger or smaller sets can be used.</p>
<p>Here are two examples:<br />
<strong>1) The christmas bauble</strong><sup>**/*****</sup><br />
<a href="https://justpuzzles.wordpress.com/2017/12/15/christmas-2017/dominosa-christmas-ball-2017-12-08-exercise/" rel="attachment wp-att-5285"><img loading="lazy" data-attachment-id="5285" data-permalink="https://justpuzzles.wordpress.com/2017/12/15/christmas-2017/dominosa-christmas-ball-2017-12-08-exercise/" data-orig-file="https://justpuzzles.files.wordpress.com/2017/12/dominosa-christmas-ball-2017-12-08-exercise.png" data-orig-size="229,241" data-comments-opened="1" data-image-meta="{&quot;aperture&quot;:&quot;0&quot;,&quot;credit&quot;:&quot;&quot;,&quot;camera&quot;:&quot;&quot;,&quot;caption&quot;:&quot;&quot;,&quot;created_timestamp&quot;:&quot;0&quot;,&quot;copyright&quot;:&quot;&quot;,&quot;focal_length&quot;:&quot;0&quot;,&quot;iso&quot;:&quot;0&quot;,&quot;shutter_speed&quot;:&quot;0&quot;,&quot;title&quot;:&quot;&quot;,&quot;orientation&quot;:&quot;0&quot;}" data-image-title="Dominosa christmas ball 2017-12-08 exercise" data-image-description="" data-image-caption="" data-medium-file="https://justpuzzles.files.wordpress.com/2017/12/dominosa-christmas-ball-2017-12-08-exercise.png?w=229" data-large-file="https://justpuzzles.files.wordpress.com/2017/12/dominosa-christmas-ball-2017-12-08-exercise.png?w=229" src="https://justpuzzles.files.wordpress.com/2017/12/dominosa-christmas-ball-2017-12-08-exercise.png?w=229&#038;h=241" alt="" width="229" height="241" class="alignnone size-full wp-image-5285" srcset="https://justpuzzles.files.wordpress.com/2017/12/dominosa-christmas-ball-2017-12-08-exercise.png 229w, https://justpuzzles.files.wordpress.com/2017/12/dominosa-christmas-ball-2017-12-08-exercise.png?w=143&amp;h=150 143w" sizes="(max-width: 229px) 100vw, 229px" /></a><br />
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<p><strong>2) The church</strong><sup>****/*****</sup><br />
<a href="https://justpuzzles.wordpress.com/2017/12/15/christmas-2017/dominosa-church-2017-12-08-exercise/" rel="attachment wp-att-5286"><img loading="lazy" data-attachment-id="5286" data-permalink="https://justpuzzles.wordpress.com/2017/12/15/christmas-2017/dominosa-church-2017-12-08-exercise/" data-orig-file="https://justpuzzles.files.wordpress.com/2017/12/dominosa-church-2017-12-08-exercise.png" data-orig-size="248,221" data-comments-opened="1" data-image-meta="{&quot;aperture&quot;:&quot;0&quot;,&quot;credit&quot;:&quot;&quot;,&quot;camera&quot;:&quot;&quot;,&quot;caption&quot;:&quot;&quot;,&quot;created_timestamp&quot;:&quot;0&quot;,&quot;copyright&quot;:&quot;&quot;,&quot;focal_length&quot;:&quot;0&quot;,&quot;iso&quot;:&quot;0&quot;,&quot;shutter_speed&quot;:&quot;0&quot;,&quot;title&quot;:&quot;&quot;,&quot;orientation&quot;:&quot;0&quot;}" data-image-title="Dominosa church 2017-12-08 exercise" data-image-description="" data-image-caption="" data-medium-file="https://justpuzzles.files.wordpress.com/2017/12/dominosa-church-2017-12-08-exercise.png?w=248" data-large-file="https://justpuzzles.files.wordpress.com/2017/12/dominosa-church-2017-12-08-exercise.png?w=248" src="https://justpuzzles.files.wordpress.com/2017/12/dominosa-church-2017-12-08-exercise.png?w=248&#038;h=221" alt="" width="248" height="221" class="alignnone size-full wp-image-5286" srcset="https://justpuzzles.files.wordpress.com/2017/12/dominosa-church-2017-12-08-exercise.png 248w, https://justpuzzles.files.wordpress.com/2017/12/dominosa-church-2017-12-08-exercise.png?w=150&amp;h=134 150w" sizes="(max-width: 248px) 100vw, 248px" /></a><br />
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<p> You can check your solution <a href="https://justpuzzles.wordpress.com/Solutions to puzzles 250-500/#367">here</a></p>
<p><strong>3) Solving strategies</strong><br />
<strong>a) Counts</strong><br />
Make a count of how often all combinations appear. To do so, list all dominoes and how often they appear in the puzzle:<br />
0-0: 2<br />
1-0: 3<br />
1-1: 5<br />
2-0: 2<br />
2-1: 1<br />
2-2: 3<br />
and so on.<br />
This will give you the position of 2-1. Mark the borders on the printed puzzle.</p>
<p><strong>b) Cross off deleted connections</strong><br />
<a href="https://justpuzzles.wordpress.com/2017/12/15/christmas-2017/dominosa-example-of-play-3/" rel="attachment wp-att-5297"><img loading="lazy" data-attachment-id="5297" data-permalink="https://justpuzzles.wordpress.com/2017/12/15/christmas-2017/dominosa-example-of-play-3/" data-orig-file="https://justpuzzles.files.wordpress.com/2017/12/dominosa-example-of-play2.png" data-orig-size="172,143" data-comments-opened="1" data-image-meta="{&quot;aperture&quot;:&quot;0&quot;,&quot;credit&quot;:&quot;&quot;,&quot;camera&quot;:&quot;&quot;,&quot;caption&quot;:&quot;&quot;,&quot;created_timestamp&quot;:&quot;0&quot;,&quot;copyright&quot;:&quot;&quot;,&quot;focal_length&quot;:&quot;0&quot;,&quot;iso&quot;:&quot;0&quot;,&quot;shutter_speed&quot;:&quot;0&quot;,&quot;title&quot;:&quot;&quot;,&quot;orientation&quot;:&quot;0&quot;}" data-image-title="dominosa example of play" data-image-description="" data-image-caption="" data-medium-file="https://justpuzzles.files.wordpress.com/2017/12/dominosa-example-of-play2.png?w=172" data-large-file="https://justpuzzles.files.wordpress.com/2017/12/dominosa-example-of-play2.png?w=172" src="https://justpuzzles.files.wordpress.com/2017/12/dominosa-example-of-play2.png?w=172&#038;h=143" alt="" width="172" height="143" class="alignnone size-full wp-image-5297" srcset="https://justpuzzles.files.wordpress.com/2017/12/dominosa-example-of-play2.png 172w, https://justpuzzles.files.wordpress.com/2017/12/dominosa-example-of-play2.png?w=150&amp;h=125 150w" sizes="(max-width: 172px) 100vw, 172px" /></a><br />
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Continuing the above example, it is easy to jump to a conclusion about 3-3, but before that we have some bookkeeping to do. Identifying the domino severed a number of links. In our example the severed links are the 3-1, 6-1, 2-0, and 5-2. When we update our list above for these severed links, we find that the number of 2-0 combinations is now reduced to 1, giving another domino.</p>
<p><strong>c) Unique positions.</strong><br />
<a href="https://justpuzzles.wordpress.com/2017/12/15/christmas-2017/dominosa-example-of-play2/" rel="attachment wp-att-5298"><img loading="lazy" data-attachment-id="5298" data-permalink="https://justpuzzles.wordpress.com/2017/12/15/christmas-2017/dominosa-example-of-play2/" data-orig-file="https://justpuzzles.files.wordpress.com/2017/12/dominosa-example-of-play21.png" data-orig-size="172,144" data-comments-opened="1" data-image-meta="{&quot;aperture&quot;:&quot;0&quot;,&quot;credit&quot;:&quot;&quot;,&quot;camera&quot;:&quot;&quot;,&quot;caption&quot;:&quot;&quot;,&quot;created_timestamp&quot;:&quot;0&quot;,&quot;copyright&quot;:&quot;&quot;,&quot;focal_length&quot;:&quot;0&quot;,&quot;iso&quot;:&quot;0&quot;,&quot;shutter_speed&quot;:&quot;0&quot;,&quot;title&quot;:&quot;&quot;,&quot;orientation&quot;:&quot;0&quot;}" data-image-title="dominosa example of play2" data-image-description="" data-image-caption="" data-medium-file="https://justpuzzles.files.wordpress.com/2017/12/dominosa-example-of-play21.png?w=172" data-large-file="https://justpuzzles.files.wordpress.com/2017/12/dominosa-example-of-play21.png?w=172" src="https://justpuzzles.files.wordpress.com/2017/12/dominosa-example-of-play21.png?w=172&#038;h=144" alt="" width="172" height="144" class="alignnone size-full wp-image-5298" srcset="https://justpuzzles.files.wordpress.com/2017/12/dominosa-example-of-play21.png 172w, https://justpuzzles.files.wordpress.com/2017/12/dominosa-example-of-play21.png?w=150&amp;h=126 150w" sizes="(max-width: 172px) 100vw, 172px" /></a><br />
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In this diagram, it is easy to see that in the top left position, only-the 3-3 is possible. </p>
<p><strong>d) Block impossible links</strong><br />
Identifying the 3-3 domino blocks the link between all other 3-3 combinations:<br />
<a href="https://justpuzzles.wordpress.com/2017/12/15/christmas-2017/dominosa-example-of-play3-2/" rel="attachment wp-att-5301"><img loading="lazy" data-attachment-id="5301" data-permalink="https://justpuzzles.wordpress.com/2017/12/15/christmas-2017/dominosa-example-of-play3-2/" data-orig-file="https://justpuzzles.files.wordpress.com/2017/12/dominosa-example-of-play31.png" data-orig-size="172,145" data-comments-opened="1" data-image-meta="{&quot;aperture&quot;:&quot;0&quot;,&quot;credit&quot;:&quot;&quot;,&quot;camera&quot;:&quot;&quot;,&quot;caption&quot;:&quot;&quot;,&quot;created_timestamp&quot;:&quot;0&quot;,&quot;copyright&quot;:&quot;&quot;,&quot;focal_length&quot;:&quot;0&quot;,&quot;iso&quot;:&quot;0&quot;,&quot;shutter_speed&quot;:&quot;0&quot;,&quot;title&quot;:&quot;&quot;,&quot;orientation&quot;:&quot;0&quot;}" data-image-title="dominosa example of play3" data-image-description="" data-image-caption="" data-medium-file="https://justpuzzles.files.wordpress.com/2017/12/dominosa-example-of-play31.png?w=172" data-large-file="https://justpuzzles.files.wordpress.com/2017/12/dominosa-example-of-play31.png?w=172" src="https://justpuzzles.files.wordpress.com/2017/12/dominosa-example-of-play31.png?w=172&#038;h=145" alt="" width="172" height="145" class="alignnone size-full wp-image-5301" srcset="https://justpuzzles.files.wordpress.com/2017/12/dominosa-example-of-play31.png 172w, https://justpuzzles.files.wordpress.com/2017/12/dominosa-example-of-play31.png?w=150&amp;h=126 150w" sizes="(max-width: 172px) 100vw, 172px" /></a><br />
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This in turn, will in some situations trigger another situation like in step c)</p>
<p>New puzzles are published at least twice a month on Fridays. Solutions are usually published after one or more weeks.</p>
<p>External links:<br />
<a href="https://www.puzzle-dominosa.com/" rel="nofollow">https://www.puzzle-dominosa.com/</a> &#8211; play them online<br />
<a href="https://www.chiark.greenend.org.uk/~sgtatham/puzzles/js/dominosa.html" rel="nofollow">https://www.chiark.greenend.org.uk/~sgtatham/puzzles/js/dominosa.html</a> &#8211; another online game site<br />
<a href="http://medmunds.github.io/puzzles/dominosa.html" rel="nofollow">http://medmunds.github.io/puzzles/dominosa.html</a> &#8211; 3rd in line play<br />
<a href="https://play.google.com/store/apps/details?id=com.oxothuk.dominosa" rel="nofollow">https://play.google.com/store/apps/details?id=com.oxothuk.dominosa</a> &#8211; android app<br />
<a href="http://www.mathematica-journal.com/2014/10/three-ways-to-solve-domino-grids/" rel="nofollow">http://www.mathematica-journal.com/2014/10/three-ways-to-solve-domino-grids/</a> &#8211; three ways to solve them.</p>
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