In a class test for Linear Programming, my professor deducted some marks because I missed the condition $y_i \leq 1$ in the mixed strategy games solution.
$ y_i $ stands for the probability of any step a player can make. My exact statement for $y_i$ was:
$$ \sum_{i = 1}^{n}{y_i} = 1 \tag{$y_i \geq 0\ \ \text{ where } \ \ i = 1,2, \cdots, n$} $$ I kept on saying that since all probabilities are non-zero and summing to $1$, none of them can ever exceed the value $1$ itself. Was I wrong in declaring like that? Or is it wrong to skip mentioning that
$$ 0 \leq y_i \leq 1 \tag{$i = 1,2, \cdots, n$} $$
You are correct. In fact, adding the redundant upper bound on the individual variables creates a small complication for the solver. With the upper bound each $y_i$ has two possible nonbasic values, 0 and 1.