text: 11.2 The Real World is Messy 
  The other reason for SHACL is that real world data is messy. Over the span of this tutorial, you may 
  have experienced a point where you made an error, and the reasoner marked your ontology as invalid. If 
  you haven’t, congratulations, but as you work with Protégé more you will experience it. This is another 
  by product of using a logic-based language. Simply having one inconsistency makes the entire model 
  invalid. For small examples this is not a problem. When one has tens, hundreds, or even thousands of 
  individuals it isn’t that difficult to find the problem and fix it. However, when dealing with Big Data 
  where one has tens of thousands, millions, or more individuals the prevalence of bad data may be huge. 
  
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