Algorithm to detect overlapping periods [duplicate]

Answer 1

This is my solution:

public static bool OverlappingPeriods(DateTime aStart, DateTime aEnd,
                                      DateTime bStart, DateTime bEnd)
{
    if (aStart > aEnd)
        throw new ArgumentException("A start can not be after its end.");

    if(bStart > bEnd)
        throw new ArgumentException("B start can not be after its end.");

    return !((aEnd < bStart && aStart < bStart) ||
                (bEnd < aStart && bStart < aStart));
}

I unit tested it with 100% coverage.