. . .
BPs sorted left are tagged with the keyword "abstract" on the OEBP. The solution is not an easily-checked or concretely-defined geometrical or numerical property in pictures.
Adjacent-numbered pages: BP507 BP508 BP509 BP510 BP511  *  BP513 BP514 BP515 BP516 BP517
abstract, meta (see left/right), links, keyword, left-self, sideless
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Aaron David Fairbanks