Problem $4$:

Voting $2$ out of $4$ logic is a redundancy scheme utilized in control systems to enhance reliability. It operates by evaluating four input signals and generating a single output based on the majority vote of those inputs. Specifically, the output signal becomes active only when at least two of the input signals are active.

$$ Inputs: The voting logic requires four input signals $($A$,$ B$,$ C$,$ and D$),$ each originating from distinct sources or sensors$.$

Output: A solitary output signal $($designated as Y $)$ is produced based on the majority vote result of the inputs.

Logic Gates: The inputs are connected to a series of AND and OR gates that implement the $2$ out of $4$ voting logic.

Voting: The logic gates are arranged in such a way that the system requires at least two inputs to be in the same state $($either high or low$)$ to consider the input valid.