bitmap index and distinct values

I was doing some reading on the internet about bitmap index suitability as it relates to the number of distinct values. I came across several links 1
<http://www.dba-oracle.com/t_bitmap_index_maximum_distinct_values_cardinality.htm>,
2
<https://richardfoote.wordpress.com/2010/02/18/myth-bitmap-indexes-with-high-distinct-columns-blow-out/>,
3 related to the topic. It seems what needs to be considered is the ratio of distinct values of a column to the total number of rows in the table rather than considering an absolute number (like over 1,000 or 10,000). Can someone explain or point to a more descriptive link.

CP.

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