Not well tested, but 

$_ = 'A A Jones'; s[(?<=[A-Z])(?=\s)][.]g; print;;
A. A. Jones

$_ = 'Bob J Smith'; s[(?<=[A-Z])(?=\s)][.]g; print;;
Bob J. Smith

$_ = 'Dr P J van Houten'; s[(?<=[A-Z])(?=\s)][.]g; print;;
Dr P. J. van Houten

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In reply to Re: simpler regex by BrowserUk
in thread simpler regex by rsiedl

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