A strong basis in the futures market means that the basis becomes larger, that is, the absolute value of the basis in the reverse market becomes larger and the absolute value of the basis in the forward market becomes smaller, but I would like to ask about the basis expansion. Generally speaking, the basis is positive, but it is not easy to say so in the book. If the formula is applied, it can only be clarified by absolute value.

In fact, we don't have to consider the absolute value. What is directly reduced is the spread of the basis, that is, the spread between the two becomes larger, that is, stronger.