Running this with use strict reveals a helpful error:

  Global symbol "%P" requires explicit package name
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in the line containing @e = $@{$P{'E'}};

$P is a reference, whereas $P{'E'} refers to a simple hash variable, called %P. Since you wish to use the reference, you will need to dereference it back to the hash %$P, using either:

  $$P{'E'}
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or

  $P->{'E'}
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Now, since that is also a reference to an array, you will need to dereference that with;

  @{$P->{'E'}}
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So the line which strict reports in error should be:

  @e = @{$P->{'E'}};
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Hope that helped,
use strict; # it's the right thing to do
-v