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	<id>https://www.sudopedia.org/index.php?action=history&amp;feed=atom&amp;title=ALS</id>
	<title>ALS - Revision history</title>
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	<updated>2026-04-29T05:53:56Z</updated>
	<subtitle>Revision history for this page on the wiki</subtitle>
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	<entry>
		<id>https://www.sudopedia.org/index.php?title=ALS&amp;diff=289&amp;oldid=prev</id>
		<title>Rooted: Redirected page to Almost Locked Set</title>
		<link rel="alternate" type="text/html" href="https://www.sudopedia.org/index.php?title=ALS&amp;diff=289&amp;oldid=prev"/>
		<updated>2020-06-04T03:12:39Z</updated>

		<summary type="html">&lt;p&gt;Redirected page to &lt;a href=&quot;/wiki/Almost_Locked_Set&quot; title=&quot;Almost Locked Set&quot;&gt;Almost Locked Set&lt;/a&gt;&lt;/p&gt;
&lt;table class=&quot;diff diff-contentalign-left&quot; data-mw=&quot;interface&quot;&gt;
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				&lt;td colspan=&quot;2&quot; style=&quot;background-color: #fff; color: #222; text-align: center;&quot;&gt;← Older revision&lt;/td&gt;
				&lt;td colspan=&quot;2&quot; style=&quot;background-color: #fff; color: #222; text-align: center;&quot;&gt;Revision as of 03:12, 4 June 2020&lt;/td&gt;
				&lt;/tr&gt;&lt;tr&gt;&lt;td colspan=&quot;2&quot; class=&quot;diff-lineno&quot; id=&quot;mw-diff-left-l1&quot; &gt;Line 1:&lt;/td&gt;
&lt;td colspan=&quot;2&quot; class=&quot;diff-lineno&quot;&gt;Line 1:&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;−&lt;/td&gt;&lt;td style=&quot;color: #222; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;&lt;del class=&quot;diffchange diffchange-inline&quot;&gt;An '''Almost Locked Set''' is a group of '''N''' [[cell]]s in a single [[house]] with [[candidate]]s for '''N+1''' [[digit]]s. In other words, it is one cell short from being a [[locked set]].&lt;/del&gt;&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;+&lt;/td&gt;&lt;td style=&quot;color: #222; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;&lt;ins class=&quot;diffchange diffchange-inline&quot;&gt;#REDIRECT &lt;/ins&gt;[[Almost Locked &lt;ins class=&quot;diffchange diffchange-inline&quot;&gt;Set&lt;/ins&gt;]]&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;−&lt;/td&gt;&lt;td style=&quot;color: #222; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt; &lt;/div&gt;&lt;/td&gt;&lt;td colspan=&quot;2&quot;&gt; &lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;−&lt;/td&gt;&lt;td style=&quot;color: #222; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;&lt;del class=&quot;diffchange diffchange-inline&quot;&gt;The simplest '''ALS''' is a single cell with 2 candidates. In a standard Sudoku an ALS can have a maximum size of 8 cells with 9 candidate digits.&lt;/del&gt;&lt;/div&gt;&lt;/td&gt;&lt;td colspan=&quot;2&quot;&gt; &lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;−&lt;/td&gt;&lt;td style=&quot;color: #222; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt; &lt;/div&gt;&lt;/td&gt;&lt;td colspan=&quot;2&quot;&gt; &lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;−&lt;/td&gt;&lt;td style=&quot;color: #222; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;&lt;del class=&quot;diffchange diffchange-inline&quot;&gt;It is not easy to spot a large ALS, but there are often a lot of these sets present in the grid. [[Bivalue]] cells are always easy to spot with [&lt;/del&gt;[&lt;del class=&quot;diffchange diffchange-inline&quot;&gt;pencilmark]]s.&lt;/del&gt;&lt;/div&gt;&lt;/td&gt;&lt;td colspan=&quot;2&quot;&gt; &lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;−&lt;/td&gt;&lt;td style=&quot;color: #222; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt; &lt;/div&gt;&lt;/td&gt;&lt;td colspan=&quot;2&quot;&gt; &lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;−&lt;/td&gt;&lt;td style=&quot;color: #222; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;&lt;del class=&quot;diffchange diffchange-inline&quot;&gt;== Usage ==&lt;/del&gt;&lt;/div&gt;&lt;/td&gt;&lt;td colspan=&quot;2&quot;&gt; &lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;−&lt;/td&gt;&lt;td style=&quot;color: #222; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;&lt;del class=&quot;diffchange diffchange-inline&quot;&gt;There are several &lt;/del&gt;[&lt;del class=&quot;diffchange diffchange-inline&quot;&gt;[solving technique]]s that make use of &lt;/del&gt;Almost Locked &lt;del class=&quot;diffchange diffchange-inline&quot;&gt;Sets. Any move that would eliminate all candidates for a particular digit from the ALS automatically forces the remaining digits to be locked in the group of cells. This the equivalent of a [[strong link]], which can be used in [[chain]]s and [[loop]]s.&lt;/del&gt;&lt;/div&gt;&lt;/td&gt;&lt;td colspan=&quot;2&quot;&gt; &lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;−&lt;/td&gt;&lt;td style=&quot;color: #222; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt; &lt;/div&gt;&lt;/td&gt;&lt;td colspan=&quot;2&quot;&gt; &lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;−&lt;/td&gt;&lt;td style=&quot;color: #222; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;&lt;del class=&quot;diffchange diffchange-inline&quot;&gt;The [[ALS-XZ]] technique uses only 2 Almost Locked Sets to perform eliminations. It is the most basic ALS technique.&lt;/del&gt;&lt;/div&gt;&lt;/td&gt;&lt;td colspan=&quot;2&quot;&gt; &lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;−&lt;/td&gt;&lt;td style=&quot;color: #222; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt; &lt;/div&gt;&lt;/td&gt;&lt;td colspan=&quot;2&quot;&gt; &lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;−&lt;/td&gt;&lt;td style=&quot;color: #222; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;&lt;del class=&quot;diffchange diffchange-inline&quot;&gt;== See also ==&lt;/del&gt;&lt;/div&gt;&lt;/td&gt;&lt;td colspan=&quot;2&quot;&gt; &lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;−&lt;/td&gt;&lt;td style=&quot;color: #222; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;&lt;del class=&quot;diffchange diffchange-inline&quot;&gt;* [[ALS-XZ]]&lt;/del&gt;&lt;/div&gt;&lt;/td&gt;&lt;td colspan=&quot;2&quot;&gt; &lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;−&lt;/td&gt;&lt;td style=&quot;color: #222; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;&lt;del class=&quot;diffchange diffchange-inline&quot;&gt;* [[ALS-XY-Wing]]&lt;/del&gt;&lt;/div&gt;&lt;/td&gt;&lt;td colspan=&quot;2&quot;&gt; &lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;−&lt;/td&gt;&lt;td style=&quot;color: #222; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;&lt;del class=&quot;diffchange diffchange-inline&quot;&gt;* [[ALS-XY-Chain]]&lt;/del&gt;&lt;/div&gt;&lt;/td&gt;&lt;td colspan=&quot;2&quot;&gt; &lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;−&lt;/td&gt;&lt;td style=&quot;color: #222; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;&lt;del class=&quot;diffchange diffchange-inline&quot;&gt;* [[Death Blossom]]&lt;/del&gt;&lt;/div&gt;&lt;/td&gt;&lt;td colspan=&quot;2&quot;&gt; &lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;−&lt;/td&gt;&lt;td style=&quot;color: #222; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;&lt;del class=&quot;diffchange diffchange-inline&quot;&gt;* [[Almost ALS&lt;/del&gt;]]&lt;/div&gt;&lt;/td&gt;&lt;td colspan=&quot;2&quot;&gt; &lt;/td&gt;&lt;/tr&gt;
&lt;/table&gt;</summary>
		<author><name>Rooted</name></author>
		
	</entry>
	<entry>
		<id>https://www.sudopedia.org/index.php?title=ALS&amp;diff=287&amp;oldid=prev</id>
		<title>Rooted: Created page with &quot;An '''Almost Locked Set''' is a group of '''N''' cells in a single house with candidates for '''N+1''' digits. In other words, it is one cell short from being...&quot;</title>
		<link rel="alternate" type="text/html" href="https://www.sudopedia.org/index.php?title=ALS&amp;diff=287&amp;oldid=prev"/>
		<updated>2020-06-04T03:11:11Z</updated>

		<summary type="html">&lt;p&gt;Created page with &amp;quot;An &amp;#039;&amp;#039;&amp;#039;Almost Locked Set&amp;#039;&amp;#039;&amp;#039; is a group of &amp;#039;&amp;#039;&amp;#039;N&amp;#039;&amp;#039;&amp;#039; &lt;a href=&quot;/wiki/Cell&quot; title=&quot;Cell&quot;&gt;cells&lt;/a&gt; in a single &lt;a href=&quot;/wiki/House&quot; title=&quot;House&quot;&gt;house&lt;/a&gt; with &lt;a href=&quot;/wiki/Candidate&quot; title=&quot;Candidate&quot;&gt;candidates&lt;/a&gt; for &amp;#039;&amp;#039;&amp;#039;N+1&amp;#039;&amp;#039;&amp;#039; &lt;a href=&quot;/wiki/Digit&quot; title=&quot;Digit&quot;&gt;digits&lt;/a&gt;. In other words, it is one cell short from being...&amp;quot;&lt;/p&gt;
&lt;p&gt;&lt;b&gt;New page&lt;/b&gt;&lt;/p&gt;&lt;div&gt;An '''Almost Locked Set''' is a group of '''N''' [[cell]]s in a single [[house]] with [[candidate]]s for '''N+1''' [[digit]]s. In other words, it is one cell short from being a [[locked set]].&lt;br /&gt;
&lt;br /&gt;
The simplest '''ALS''' is a single cell with 2 candidates. In a standard Sudoku an ALS can have a maximum size of 8 cells with 9 candidate digits.&lt;br /&gt;
&lt;br /&gt;
It is not easy to spot a large ALS, but there are often a lot of these sets present in the grid. [[Bivalue]] cells are always easy to spot with [[pencilmark]]s.&lt;br /&gt;
&lt;br /&gt;
== Usage ==&lt;br /&gt;
There are several [[solving technique]]s that make use of Almost Locked Sets. Any move that would eliminate all candidates for a particular digit from the ALS automatically forces the remaining digits to be locked in the group of cells. This the equivalent of a [[strong link]], which can be used in [[chain]]s and [[loop]]s.&lt;br /&gt;
&lt;br /&gt;
The [[ALS-XZ]] technique uses only 2 Almost Locked Sets to perform eliminations. It is the most basic ALS technique.&lt;br /&gt;
&lt;br /&gt;
== See also ==&lt;br /&gt;
* [[ALS-XZ]]&lt;br /&gt;
* [[ALS-XY-Wing]]&lt;br /&gt;
* [[ALS-XY-Chain]]&lt;br /&gt;
* [[Death Blossom]]&lt;br /&gt;
* [[Almost ALS]]&lt;/div&gt;</summary>
		<author><name>Rooted</name></author>
		
	</entry>
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