Answers.Body: <p>Because this is more of an answer than a comment:</p>
  
  <blockquote>
    <p>In the add connection
    mutation, a single new connection gene with a random weight is added connecting
    two previously unconnected nodes. </p>
  </blockquote>
  
  <p>So two nodes that have been mutated with a connection, can't remutate because the nodes should be unconnected.</p>
  
  <blockquote>
    <p>In the add node mutation, an existing connection is
    split and the new node placed where the old connection used to be. The old connection
    is disabled and two new connections are added to the genome.</p>
  </blockquote>
  
  <p>The old connection is disabled, so the same mutation can't occur again on this connection. In practice, you can just remove the disabled connection, because it will be formed again with the add connection mutation.</p>
  
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2017-05-06T14:42:58.113Z
Answers.Text: Okay. I must have over read the previously unconnected part. Thanks
Answers.UserDisplayName: Miemels
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2017-05-06T14:39:52.057Z
Answers.LastActivityDate: 2017-05-06T14:39:52.057Z
Answers.UserDisplayName: Thomas Wagenaar
Body: <p>I´m currently implementing NEAT.
  What should I do when in a mutation the same Innovation occurs which has already happened to that genome?</p>
  
  <p>Should I simply ignore it?</p>
  
  <p>If not what do I do with it in the mating part?</p>
  
Comments.ContentLicense: CC BY-SA 3.0
Comments.CreationDate: 2017-05-06T14:27:46.127Z
Comments.Text: What do you mean exactly? The NEAT algorithm doesn't make it possible that the same innovation occurs twice in the same genome.
Comments.UserDisplayName: Thomas Wagenaar
Comments.ContentLicense: CC BY-SA 3.0
Comments.CreationDate: 2017-05-06T14:29:48.333Z
Comments.Text: @ThomasW where exactly does he says this. I can´t remember reading this.
Comments.UserDisplayName: Miemels
Tags: <neural-networks><evolutionary-algorithms><neat>
Title: What to do with duplicate Innovations in a genome?
UserDisplayName: Miemels
ThreadText: # What to do with duplicate Innovations in a genome?
  
  (Asked by: username_0 on 2017-05-06)
  
  I´m currently implementing NEAT.
  What should I do when in a mutation the same Innovation occurs which has already happened to that genome?
  
  Should I simply ignore it?
  
  If not what do I do with it in the mating part?
  
  **Tags:** neural-networks, evolutionary-algorithms, neat
  
  > **Comments:**
  > **username_1**: What do you mean exactly? The NEAT algorithm doesn't make it possible that the same innovation occurs twice in the same genome.  
  > **username_0**: @ThomasW where exactly does he says this. I can´t remember reading this.  
  
  ---
  
  ## 1 answers
  
  ### Answer by username_1 on 2017-05-06. Score: 3 | Accepted answer
  
  Because this is more of an answer than a comment:
  
  > In the add connection
  > mutation, a single new connection gene with a random weight is added connecting
  > two previously unconnected nodes.
  
  So two nodes that have been mutated with a connection, can't remutate because the nodes should be unconnected.
  
  > In the add node mutation, an existing connection is
  > split and the new node placed where the old connection used to be. The old connection
  > is disabled and two new connections are added to the genome.
  
  The old connection is disabled, so the same mutation can't occur again on this connection. In practice, you can just remove the disabled connection, because it will be formed again with the add connection mutation.
  
  > **Comments:**
  > **username_0**: Okay. I must have over read the previously unconnected part. Thanks  
  
  ---
  
  