List-obstruction 1
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available colours vertex 0: 1 
available colours vertex 1: 1 2 
available colours vertex 2: 2 
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List-obstruction 2
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1 : 0 2
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available colours vertex 0: 1 
available colours vertex 1: 1 2 
available colours vertex 2: 1 2 
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List-obstruction 3
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available colours vertex 0: 1 
available colours vertex 1: 1 2 
available colours vertex 2: 2 
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List-obstruction 4
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available colours vertex 0: 1 2 
available colours vertex 1: 1 2 
available colours vertex 2: 1 2