Case 1: Suppose the questioner means that the number of weeks yesterday and tomorrow are exactly the same, in other words, yesterday's date and tomorrow's date are exactly the same, for example, yesterday was Sunday on February 15, and tomorrow is also Sunday on February 15, that is, if a=b, then b must be equal to a;
The second situation is that the questioner means that yesterday was Monday, today is Monday A plus one day, and tomorrow is Monday A plus two days. In other words, if yesterday's "week A" wants to become tomorrow's "week B", it must add two days, that is, push yesterday forward by two days, and the expression A+2 = "week B". If we push back two or several days, there will be no relationship between yesterday and tomorrow, but the relationship between the day before yesterday, the day before yesterday and the day before yesterday. Objectively speaking, there is always a difference of two days between yesterday and tomorrow. Yesterday, pushing forward two days is tomorrow, tomorrow, pushing back two days is yesterday.
Let's see the situation first. From the topic "So today is Friday", we can first deduce that "hypothetical yesterday" is Thursday, and from "If only yesterday were tomorrow", we can also deduce that "hypothetical tomorrow" is Thursday. Of course, it can't be that yesterday was Thursday and tomorrow is Thursday. Daydreaming is ok, but here is just to find the answer to the hypothesis in the topic. If "hypothetical tomorrow" is also Thursday, then "hypothetical today" is Wednesday, which does not meet the assumption of "so today is Friday" in the title, so it is not established.
According to the above situation, this time we derive "hypothetical tomorrow" from the topic "So today is Friday", so it is Saturday, and "hypothetical yesterday" is Thursday from "If only yesterday were tomorrow", which means that "hypothetical yesterday" must be pushed forward two days to become "hypothetical tomorrow Saturday", and the real today must be pushed forward two days to get "hypothetical today". The children's shoes on Sunday were obtained because the original saying "If only yesterday were tomorrow" is equivalent to "If only tomorrow were yesterday". Using an expression to indicate that if a=b, then b = a is a constant formula in mathematics, but children's shoes who have studied computer programming should know that if a=b, then B is not necessarily equal to A, because there are not only equal signs = in programming, but also double equal signs = =. Generally, people who get the answer on Sunday will use the alternative answer to push the question, that is, by applying the formula, take a bunch of keys to open a lock, and which key is opened, assuming it is the original key. Unexpectedly, this may not be the case. Some locks can also be opened with keys of other locks similar to the original key. Most people have this formula: Sunday is today, Saturday is yesterday, yesterday is tomorrow, tomorrow is Saturday and today is Friday, so it is correct. As we all know, it is reasonable for you to change it like this, but the result is not Friday: Sunday is today, Monday is tomorrow, then yesterday is tomorrow, yesterday is Monday, and today is Tuesday. Such an algorithm is completely wrong. This problem can not be solved by a set of mathematical formulas, but also depends on whether the solving process and the answer operator conform to objective facts.
Summary: Because the question itself is vague, it leads to many answers. It is not a qualified application problem, but a common problem in life. After all, many people in life have assumed this problem. On Wednesday, you always think, if yesterday is tomorrow, to put it bluntly, if yesterday Tuesday is tomorrow Thursday, then I will work last Friday. Isn't it the weekend after work today? Who will say on Sunday: "If yesterday's Saturday is tomorrow's Monday, then today's class is Tuesday. Do you like work so much? " So the real answer is Wednesday, and the divergent answer is Friday. Do not believe in asking the original author of the question.