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<b>let </b><font color="Maroon">K</font> be  non <a href="struct_0.html#V3">empty</a> <a href="rlvect_1.html#V3">Abelian</a> <a href="rlvect_1.html#V4">add-associative</a> <a href="rlvect_1.html#V5">right_zeroed</a> <a href="rlvect_1.html#V6">right_complementable</a> <a href="group_1.html#V4">associative</a> <a href="vectsp_1.html#V7">distributive</a> <a href="vectsp_1.html#V8">left_unital</a>  <a href="vectsp_1.html#L3">doubleLoopStr</a> ;<br/><b>let </b><font color="Maroon">V</font> be   <a href="vectsp_1.html#NM6">VectSp</a> of <font color="Maroon">K</font>;<br/><b>let </b><font color="Maroon">W1</font> be    <a href="vectsp_4.html#M1">Subspace</a> of <font color="Maroon">V</font>, <font color="Maroon">W2</font> be    <a href="vectsp_4.html#M1">Subspace</a> of <font color="Maroon">V</font>;<br/>





<b>assume </b><a NAME="E1:20"/><i><font color="Green">E29</font></i>: 
<font color="Maroon">V</font> <a href="vectsp_5.html#R1">is_the_direct_sum_of</a> <font color="Maroon">W1</font>,<font color="Maroon">W2</font>
 ;<br/>

<a NAME="E2:20"/><b>then </b><i><font color="Green">E35</font></i>: 
<font color="Maroon">V</font> <a href="vectsp_5.html#R1">is_the_direct_sum_of</a> <font color="Maroon">W2</font>,<font color="Maroon">W1</font>
 
<b>by </b><i><a class="ref" href="vectsp_5.html#T51">VECTSP_5:51</a></i>;<br/>
<b>let </b><font color="Maroon">v</font> be   <a href="vectsp_1.html#NM5">Vector</a> of <font color="Maroon">V</font>, <font color="Maroon">v1</font> be   <a href="vectsp_1.html#NM5">Vector</a> of <font color="Maroon">V</font>, <font color="Maroon">v2</font> be   <a href="vectsp_1.html#NM5">Vector</a> of <font color="Maroon">V</font>;<br/>

<b>assume </b><a NAME="E3:20"/>
<font color="Maroon">v</font> <a href="vectsp_5.html#K4">|--</a> <font color="Maroon">W1</font>,<font color="Maroon">W2</font> <a href="hidden.html#R1">=</a> <span class="p1"><a href="domain_1.html#K1">[</a><span class="default"><font color="Maroon">v1</font>,<font color="Maroon">v2</font></span><a href="domain_1.html#K1">]</a></span>
 ;<br/>

<a NAME="E4:20"/><b>then </b><i><font color="Green">E42</font></i>: 
( <span class="p1">(<span class="default"><font color="Maroon">v</font> <a href="vectsp_5.html#K4">|--</a> <font color="Maroon">W1</font>,<font color="Maroon">W2</font></span>)</span> <a href="domain_1.html#K2">`1</a>  <a href="hidden.html#R1">=</a> <font color="Maroon">v1</font> &amp; <span class="p1">(<span class="default"><font color="Maroon">v</font> <a href="vectsp_5.html#K4">|--</a> <font color="Maroon">W1</font>,<font color="Maroon">W2</font></span>)</span> <a href="domain_1.html#K3">`2</a>  <a href="hidden.html#R1">=</a> <font color="Maroon">v2</font> )
 
<b>by </b><i><a class="ref" href="mcart_1.html#T7">MCART_1:7</a></i>;<br/>
<a NAME="E5:20"/><b>then </b><i><font color="Green">E46</font></i>: 
( <font color="Maroon">v1</font> <a href="rlvect_1.html#R1">in</a> <font color="Maroon">W1</font> &amp; <font color="Maroon">v2</font> <a href="rlvect_1.html#R1">in</a> <font color="Maroon">W2</font> )
 
<b>by </b><i>, <a class="ref" href="vectsp_5.html#D6">VECTSP_5:def 6</a></i>;<br/>
<a NAME="E6:20"/>
<font color="Maroon">v</font> <a href="hidden.html#R1">=</a> <font color="Maroon">v2</font> <a href="rlvect_1.html#K4">+</a> <font color="Maroon">v1</font>
 
<b>by </b><i>, , <a class="ref" href="vectsp_5.html#D6">VECTSP_5:def 6</a></i>;<br/>
<b>hence </b><a NAME="E7:20"/>
<font color="Maroon">v</font> <a href="vectsp_5.html#K4">|--</a> <font color="Maroon">W2</font>,<font color="Maroon">W1</font> <a href="hidden.html#R1">=</a> <span class="p1"><a href="domain_1.html#K1">[</a><span class="default"><font color="Maroon">v2</font>,<font color="Maroon">v1</font></span><a href="domain_1.html#K1">]</a></span>
 <b>by </b><i>, , </i>;<br/>


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