<?xml version="1.0"?>


<!-- Propositional Logic formulas are defined by atomic formula, and
boolean operator and, or, neg.  
All propositional formula has an equivalent in conjunctive normal form (CNF).

A formula in CNF is defined by the following grammar (initial symbol is F)

F -> Seq_and(C)
C -> Seq_or(A)
A -> a | b | c |...| g| neg a | neg b | neg c |...| neg g

The negation symbol is not count in the size of the formula.
-->




<!DOCTYPE specification SYSTEM "seed.dtd">


<specification>
  <start idref="All"/> 

  <sequence id="All"> <!-- A CNF formula is a sequence of clause -->
    <symbol value="And"/>
    <child idref="C"/> 
  </sequence> 

  <constants_set id="C"> <!-- A clause is a set of atoms -->
    <child idref="S"/> 
  </constants_set> 



  <constants id="S"> <!-- defintion of an atom-->
    <symbol value="a"/>
    <symbol value="b"/>
    <symbol value="c"/>
    <symbol value="d"/>
    <symbol value="e"/>
    <symbol value="f"/>
    <symbol value="g"/>
    <symbol value="not a"/>
    <symbol value="not b"/>
    <symbol value="not c"/>
    <symbol value="not d"/>
    <symbol value="not e"/>
    <symbol value="not f"/>
    <symbol value="not g"/>
  </constants>


</specification>

