deletions | additions       diff --git a/It_should_be_noted_that__.tex b/It_should_be_noted_that__.tex  index 7de00f9..b280719 100644  --- a/It_should_be_noted_that__.tex  +++ b/It_should_be_noted_that__.tex 
...
The notation $N$ will be used for the total population value.  It should be noted that as these are the only categories the population may be divided into, $S+I+R=1$ $S+I+R=N$  must be case for any value of $t$.