ZHANG, Ruda August 07, 2020:  Correct math: use 1 with set subscript for characteristic function / indicator function of the set; use "[ x ]" instead of "[x]" to avoid GFM checkbox syntax. [1ac98ba]
ZHANG, Ruda March 14, 2020:  Format definitions. [d86c961]
ZHANG, Ruda December 30, 2018:  Use dollar style math markup. [1b7036c]
ZHANG, Ruda July 18, 2018:  More on MLE, MME [81a9c52]
ZHANG, Ruda July 10, 2018:  Add manifold learning [ba3d5e6]
ZHANG, Ruda March 23, 2018:  Global remove trailing whitespaces [2b7ff90]
ZHANG, Ruda November 24, 2017:  Define standard error of a statistic. [d7a028a]
ZHANG, Ruda November 24, 2017:  Reformat estimator of sample variance [0a2316d]
ZHANG, Ruda October 16, 2017:  regression and econometrics [7154d42]
ZHANG, Ruda October 16, 2017:  Sample and statistic [20d464d]