The example gets much clearer if you change "first candle" and "second candle" by "red candle" and "green candle". Further the assumption is made, that there is a non-vanishing period of time in which both candles are burning.
But I really don't know what should be the according assumption for the three candles: Does every pair of them has an overlap in common, or all three of them?
But I really don't know what should be the according assumption for the three candles: Does every pair of them has an overlap in common, or all three of them?