ZHANG, Ruda December 30, 2018:  Use dollar style math markup. [1b7036c]
ZHANG, Ruda March 23, 2018:  Global remove trailing whitespaces [2b7ff90]
Ruda Zhang June 26, 2016:  one sentence per line [e15360a]
Ruda Zhang June 26, 2016:  add category tag to wiki pages [a9b356c]
Ruda Zhang June 26, 2016:  Use internal link for wiki pages. [22daaba]
Ruda Zhang June 26, 2016:  use canonical filename and no internal H1 [eeca8ff]