Formulate a constraint for the logical conditions described in the following statements. a$)$ Projects $2$ and $6$ are mutually exclusive $($i$.$e$.,$ they cannot be chosen together$).$ b$)$ CRT$$s management wants to select two projects out of projects $1,2,4,$ and $6.$ c$)$ Project $2$ can be selected only if project $3$ is selected and vice$-$versa. d$)$ Project $5$ cannot be undertaken unless both projects $3$ and $4$ are also undertaken. e$)$ If projects $2$ and $4$ are undertaken, then project $5$ must also be undertaken.