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<!DOCTYPE proofs SYSTEM "proof3.dtd">

<?xml-stylesheet type="text/xsl" href="proof3.xsl"?>

<proofs number_of_proofs="1">

<source>bcs.out</source>

<heading><![CDATA[
Prover9 (32) version 2009-02A, February 2009.
Process 11673 was started by mccune on cleo,
Wed Feb 25 09:36:20 2009
The command was "/home/mccune/bin/prover9 -f head.in bcs.in".
]]></heading>

<proof number="1" length="24" max_count="46">

<comments><![CDATA[
% Proof 1 at 0.03 (+ 0.00) seconds.
% Length of proof is 24.
% Level of proof is 7.
% Maximum clause weight is 13.
% Given clauses 36.

]]></comments>

  <clause id="3" type="assumption">
    <literal><![CDATA[
      (all x all y all z (B(x,y,z) <-> (x ^ y) v (y ^ z) = y & (x v y) ^ (y v z) = y))
    ]]></literal>
    <attribute><![CDATA[
      label(non_clause)
    ]]></attribute>
    <justification jstring="[assumption].">
      <j1 rule="assumption"/>
    </justification>
  </clause>

  <clause id="5" type="assumption">
    <literal><![CDATA[
      (all x all y all z (CS(x,y,z) <-> (x v y) ^ (y v z) = y & (x v z) ^ y = y))
    ]]></literal>
    <attribute><![CDATA[
      label(non_clause)
    ]]></attribute>
    <justification jstring="[assumption].">
      <j1 rule="assumption"/>
    </justification>
  </clause>

  <clause id="9" type="goal">
    <literal><![CDATA[
      (all a all x all b (B(a,x,b) -> CS(a,x,b)))
    ]]></literal>
    <attribute><![CDATA[
      label(non_clause)
    ]]></attribute>
    <justification jstring="[goal].">
      <j1 rule="goal"/>
    </justification>
  </clause>

  <clause id="10" type="expand_def">
    <literal><![CDATA[
      (all a all x all b ((a ^ x) v (x ^ b) = x & (a v x) ^ (x v b) = x -> CS(a,x,b)))
    ]]></literal>
    <attribute><![CDATA[
      label(non_clause)
    ]]></attribute>
    <justification jstring="[expand_def(9,3)].">
      <j1 rule="expand_def" parents="9 3"/>
    </justification>
  </clause>

  <clause id="11" type="expand_def">
    <literal><![CDATA[
      (all a all x all b ((a ^ x) v (x ^ b) = x & (a v x) ^ (x v b) = x -> (a v x) ^ (x v b) = x & (a v b) ^ x = x))
    ]]></literal>
    <attribute><![CDATA[
      label(non_clause)
    ]]></attribute>
    <attribute><![CDATA[
      label(goal)
    ]]></attribute>
    <justification jstring="[expand_def(10,5)].">
      <j1 rule="expand_def" parents="10 5"/>
    </justification>
  </clause>

  <clause id="12" type="assumption">
    <literal><![CDATA[
      (x ^ y) v x = x
    ]]></literal>
    <attribute><![CDATA[
      label("absorption_2")
    ]]></attribute>
    <justification jstring="[assumption].">
      <j1 rule="assumption"/>
    </justification>
  </clause>

  <clause id="13" type="assumption">
    <literal><![CDATA[
      (x v y) ^ x = x
    ]]></literal>
    <attribute><![CDATA[
      label("absorption_1")
    ]]></attribute>
    <justification jstring="[assumption].">
      <j1 rule="assumption"/>
    </justification>
  </clause>

  <clause id="14" type="assumption">
    <literal><![CDATA[
      (x v y) v z = x v (y v z)
    ]]></literal>
    <attribute><![CDATA[
      label("associativity_join")
    ]]></attribute>
    <justification jstring="[assumption].">
      <j1 rule="assumption"/>
    </justification>
  </clause>

  <clause id="16" type="assumption">
    <literal><![CDATA[
      x v y = y v x
    ]]></literal>
    <attribute><![CDATA[
      label("commutativity_join")
    ]]></attribute>
    <justification jstring="[assumption].">
      <j1 rule="assumption"/>
    </justification>
  </clause>

  <clause id="17" type="assumption">
    <literal><![CDATA[
      x ^ y = y ^ x
    ]]></literal>
    <attribute><![CDATA[
      label("commutativity_meet")
    ]]></attribute>
    <justification jstring="[assumption].">
      <j1 rule="assumption"/>
    </justification>
  </clause>

  <clause id="18" type="deny">
    <literal><![CDATA[
      (c1 ^ c2) v (c2 ^ c3) = c2
    ]]></literal>
    <justification jstring="[deny(11)].">
      <j1 rule="deny" parents="11"/>
    </justification>
  </clause>

  <clause id="19" type="deny">
    <literal><![CDATA[
      (c1 v c2) ^ (c2 v c3) = c2
    ]]></literal>
    <justification jstring="[deny(11)].">
      <j1 rule="deny" parents="11"/>
    </justification>
  </clause>

  <clause id="20" type="deny">
    <literal><![CDATA[
      (c1 v c2) ^ (c2 v c3) != c2
    ]]></literal>
    <literal><![CDATA[
      (c1 v c3) ^ c2 != c2
    ]]></literal>
    <justification jstring="[deny(11)].">
      <j1 rule="deny" parents="11"/>
    </justification>
  </clause>

  <clause id="21">
    <literal><![CDATA[
      c2 ^ (c1 v c3) != c2
    ]]></literal>
    <justification jstring="[copy(20),rewrite([19(7),17(8)]),xx(a)].">
      <j1 rule="copy" parents="20"/>
      <j2 rule="rewrite" parents="19 17"/>
      <j2 rule="xx"/>
    </justification>
  </clause>

  <clause id="22">
    <literal><![CDATA[
      x v (x ^ y) = x
    ]]></literal>
    <justification jstring="[back_rewrite(12),rewrite([16(2)])].">
      <j1 rule="back_rewrite" parents="12"/>
      <j2 rule="rewrite" parents="16"/>
    </justification>
  </clause>

  <clause id="23">
    <literal><![CDATA[
      x ^ (x v y) = x
    ]]></literal>
    <justification jstring="[back_rewrite(13),rewrite([17(2)])].">
      <j1 rule="back_rewrite" parents="13"/>
      <j2 rule="rewrite" parents="17"/>
    </justification>
  </clause>

  <clause id="24">
    <literal><![CDATA[
      x v (y v z) = y v (x v z)
    ]]></literal>
    <justification jstring="[para(16(a,1),14(a,1,1)),rewrite([14(2)])].">
      <j1 rule="para" parents="16 14"/>
      <j2 rule="rewrite" parents="14"/>
    </justification>
  </clause>

  <clause id="27">
    <literal><![CDATA[
      (c2 ^ c3) v (x v (c1 ^ c2)) = x v c2
    ]]></literal>
    <justification jstring="[para(18(a,1),14(a,2,2)),rewrite([16(8)])].">
      <j1 rule="para" parents="18 14"/>
      <j2 rule="rewrite" parents="16"/>
    </justification>
  </clause>

  <clause id="32">
    <literal><![CDATA[
      x v (y ^ x) = x
    ]]></literal>
    <justification jstring="[para(17(a,1),22(a,1,2))].">
      <j1 rule="para" parents="17 22"/>
    </justification>
  </clause>

  <clause id="43">
    <literal><![CDATA[
      x ^ (y v (x v z)) = x
    ]]></literal>
    <justification jstring="[para(24(a,1),23(a,1,2))].">
      <j1 rule="para" parents="24 23"/>
    </justification>
  </clause>

  <clause id="53">
    <literal><![CDATA[
      x v (y v (z ^ x)) = y v x
    ]]></literal>
    <justification jstring="[para(32(a,1),24(a,1,2)),flip(a)].">
      <j1 rule="para" parents="32 24"/>
      <j2 rule="flip"/>
    </justification>
  </clause>

  <clause id="96">
    <literal><![CDATA[
      c1 v (c2 ^ c3) = c1 v c2
    ]]></literal>
    <justification jstring="[para(22(a,1),27(a,1,2)),rewrite([16(5)])].">
      <j1 rule="para" parents="22 27"/>
      <j2 rule="rewrite" parents="16"/>
    </justification>
  </clause>

  <clause id="142">
    <literal><![CDATA[
      c1 v (c2 v c3) = c1 v c3
    ]]></literal>
    <justification jstring="[para(96(a,1),53(a,1,2)),rewrite([24(5),16(4)])].">
      <j1 rule="para" parents="96 53"/>
      <j2 rule="rewrite" parents="24 16"/>
    </justification>
  </clause>

  <clause id="159">
    <literal><![CDATA[
      $F
    ]]></literal>
    <justification jstring="[para(142(a,1),43(a,1,2)),unit_del(a,21)].">
      <j1 rule="para" parents="142 43"/>
      <j2 rule="unit_del" parents="21"/>
    </justification>
  </clause>

</proof>

</proofs>
