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		<title>21495: HW 6 - Revision history</title>
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		<updated>2026-04-25T16:04:51Z</updated>
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		<id>http://helmut.knaust.info/mediawiki/index.php?title=21495:_HW_6&amp;diff=2151&amp;oldid=prev</id>
		<title>HelmutKnaust: Created page with &quot;'''Problem 26.'''  Consider the following equivalence relation on the set $A=\{1,2,3,4,5,6\}$: \[R=\{(1,1),(2,2),(3,3),(4,4),(5,5),(6,6),(1,2),(1,4),(2,1),(2,4),(4,1),(4,2),(3...&quot;</title>
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				<updated>2017-04-10T03:48:49Z</updated>
		
		<summary type="html">&lt;p&gt;Created page with &amp;quot;&amp;#039;&amp;#039;&amp;#039;Problem 26.&amp;#039;&amp;#039;&amp;#039;  Consider the following equivalence relation on the set $A=\{1,2,3,4,5,6\}$: \[R=\{(1,1),(2,2),(3,3),(4,4),(5,5),(6,6),(1,2),(1,4),(2,1),(2,4),(4,1),(4,2),(3...&amp;quot;&lt;/p&gt;
&lt;p&gt;&lt;b&gt;New page&lt;/b&gt;&lt;/p&gt;&lt;div&gt;'''Problem 26.'''  Consider the following equivalence relation on the set $A=\{1,2,3,4,5,6\}$:&lt;br /&gt;
\[R=\{(1,1),(2,2),(3,3),(4,4),(5,5),(6,6),(1,2),(1,4),(2,1),(2,4),(4,1),(4,2),(3,6),(6,3)\}.\]&lt;br /&gt;
Find the partition generated by $R$.&lt;br /&gt;
&lt;br /&gt;
'''Problem 27.'''  Let $R$ be a relation on $\mathbb{N}$ defined by &lt;br /&gt;
\[(p,q)\in R \Leftrightarrow p^2+q^2 \mbox{ is even.}\]&lt;br /&gt;
#Show that $R$ is an equivalence relation.&lt;br /&gt;
#Find all distinct equivalence classes of this relation.&lt;br /&gt;
&lt;br /&gt;
'''Problem 28.'''  Let $R$ and $S$ be two equivalence relations on a non-empty set $X$. Prove or disprove: &lt;br /&gt;
#$R\cap S$ is an equivalence relation. &lt;br /&gt;
#$R\cup S$ is an equivalence relation. &lt;br /&gt;
&lt;br /&gt;
'''Problem 29.'''  Consider the following relation $R$ defined on a Boolean Algebra ${\cal A}$:&lt;br /&gt;
\[(P,Q)\in R \Leftrightarrow P\sqcup Q=Q\]&lt;br /&gt;
Prove or disprove: $R$ is (a) reflexive, (b) transitive, (c) symmetric,  (d) anti-symmetric.&lt;br /&gt;
&lt;br /&gt;
'''Problem 30.'''  On the set of natural numbers $\mathbb{N}$ consider the partial order \[n\ |\ m \Leftrightarrow\ n\mbox{ is a divisor of }m.\] &lt;br /&gt;
Draw a ''Hasse diagram'' for the set $A=\{1,2,3,4,5,\ldots, 12,13,14,15\}$ endowed with this partial order.&lt;/div&gt;</summary>
		<author><name>HelmutKnaust</name></author>	</entry>

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