Sorry for the lack of clarity-I’m not talking about high school algebra, I’m talking about abstract algebra. I guess if we’re writing −2 as a simplification, that’s fine, but seems to introduce a kind of meaningless extra step-I don’t quite understand the “special cases” you’re talking about, because it seems to me that you can eliminate subtraction without doing this? In fact, for anything more abstract than calculus, that’s standard-groups, for example, don’t have subtraction defined (usually) other than as the addition of the inverse.
I guess if we’re writing −2 as a simplification, that’s fine, but seems to introduce a kind of meaningless extra step
...¯¯¯97 is the simplified form of −3, not the other way around, in the same sense that 0.¯¯¯3... is the simplified form of 3−1.
Why do we think it’s consistent that we can express a multiplicative inverse without an operator, but we can’t do the same for an additive inverse? A number system with compliments can express a negative number on its own rather than requiring you to express it in terms of a positive number and an inversion operator, but you still need the operator for other reasons. ^8 seems no more superfluous of an additive inverse of 2 than 0.5 is as its multiplicative inverse. Either both are superfluous, or neither is.
it seems to me that you can eliminate subtraction without doing this? In fact, for anything more abstract than calculus, that’s standard-groups, for example, don’t have subtraction defined (usually) other than as the addition of the inverse.
That was kind of my point, as far as the algebra is concerned—subtraction, fundamentally, is a negate and add, not a primitive. But I was talking about children doing arithmetic, and they can do it the same way. Teach them how to do negation (using complements, not tacking on a sign) instead of subtraction, and you’re done. You never have to memorize the subtraction table.
Ok, I think I understand our crux here. In the fields of math I’m talking about, 3^(-1) is a far better way to express the multiplicative inverse of 3, simply because it’s not dependent on any specific representation scheme and immediately carries the relevant meaning. I don’t know enough about the pedagogy of elementary school math to opine on that.
Sorry for the lack of clarity-I’m not talking about high school algebra, I’m talking about abstract algebra. I guess if we’re writing −2 as a simplification, that’s fine, but seems to introduce a kind of meaningless extra step-I don’t quite understand the “special cases” you’re talking about, because it seems to me that you can eliminate subtraction without doing this? In fact, for anything more abstract than calculus, that’s standard-groups, for example, don’t have subtraction defined (usually) other than as the addition of the inverse.
...¯¯¯97 is the simplified form of −3, not the other way around, in the same sense that 0.¯¯¯3... is the simplified form of 3−1.
Why do we think it’s consistent that we can express a multiplicative inverse without an operator, but we can’t do the same for an additive inverse? A number system with compliments can express a negative number on its own rather than requiring you to express it in terms of a positive number and an inversion operator, but you still need the operator for other reasons. ^8 seems no more superfluous of an additive inverse of 2 than 0.5 is as its multiplicative inverse. Either both are superfluous, or neither is.
That was kind of my point, as far as the algebra is concerned—subtraction, fundamentally, is a negate and add, not a primitive. But I was talking about children doing arithmetic, and they can do it the same way. Teach them how to do negation (using complements, not tacking on a sign) instead of subtraction, and you’re done. You never have to memorize the subtraction table.
Ok, I think I understand our crux here. In the fields of math I’m talking about, 3^(-1) is a far better way to express the multiplicative inverse of 3, simply because it’s not dependent on any specific representation scheme and immediately carries the relevant meaning. I don’t know enough about the pedagogy of elementary school math to opine on that.