deletions | additions       diff --git a/section_Theory_of_the_SIR__.tex b/section_Theory_of_the_SIR__.tex  index 2e3ae4b..2bd98b3 100644  --- a/section_Theory_of_the_SIR__.tex  +++ b/section_Theory_of_the_SIR__.tex 
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\item When an individual is removed, he/she is assumed to be immune for the remainder of his/her life, and is therefore unable to rejoin susceptible.  \item Every individual that is infected has equal probability of encountering an individual that is susceptible per unit time.   \end{enumerate}  These assumptions will obviously limit the practical usages of the model, as the model's outcomes would not represent results in a real world environment. However, the model may be adapted in order to incorporate dimensions from a real world scenario, such as that of Yellow Fever in Angola. In order to adapt the model to fit the situation, understand of the underlying, or basic model is required. This will be explained below. As stated above, individuals may be in one of three categories. The equations below show the number of people in each of the three categories as a function of time. As to be discovered, it is easier to assign fractions of the population to each of the classes, not the real values. This means that all values for $S$, $I$ and $R$ as functions of time are divided by $N$, the value of the total population. \begin{gather*} \begin{align*}  S = &=  \frac{S(t)}{N} && \text{fraction of population that is susceptible}  \\ I = &=  \frac{I(t)}{N} && \text{fraction of population that is infected}  \\ R = &=  \frac{R(t)}{N} \\  \end{gather*} && \text{fraction of population that is removed}  \end{align*}