It is also the case that mathematics deals with positive and negative numbers. These numbers are fabricated by mathematics to get around the difficulty of including addition and subtraction in mathematics proper. Thus a lost sheep implies an actual world in which sheep exist or do not exist, whereas mathematics is not supposed to recognize anything other than its ideal world from which sheep could not disappear. Another area is the number of dimensions. The last question has an answer that may clarify our whole approach.
Time is obviously necessary to a universe of becoming.
Such a world involves the learning process because there would have to be time to distinguish cause and effect. Without this distinction there could be no learning. Here the observer is really necessary. The dimensions of space are also necessary to separate the agent of cause and effect from what is not the agent. Something equivalent to mass, if not mass itself, is necessary to evaluate the scope or significance of an effect.