RewriteEngine On
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^public_html/(.+)$ wiki/index.php?title=$1 [PT,L,QSA]
RewriteRule ^public_html/*$ wiki/ [L,QSA]
RewriteRule ^/*$ wiki/ [L,QSA]