yori
Joined 7 years ago
Joined 7 years ago
This is backward reasoning. The chosen definition of multiplication is not to keep things "intuitive". If you start with the field axioms, the chosen definition of multiplication is pretty much dictated by the axioms. If you choose another definition of multiplication, you would end with contradictions like 1 = 0 and such nonsense! And mathematicians abhor contradictions!
"Product of additive inverses of two elements is equal to the product of the two elements" is dictated by the field axioms in all fields.
The assumptions made in the article are perfectly fine as per field axioms. Granted it would have been nicer if distributivity over addition was used instead of distributivity over subtraction. But it is not a big leap to derive distributivity over substraction from field axioms by distributing multiplication over a positive number and the additive inverse of another positive number.
Wherever you see an assumption made about negative number, just mentally replace it with additive inverse of a positive number and you would be fine.
And why start with Peano axioms? They seem like a bad starting point because it would take pages upon pages of proof and it won't easily extend to other algebraic structures like rings and fields.
How do you know when to use Lambert W function?
10 MODE 2
20 COLOUR RND(7)
30 PRINT "HELLO WORLD"
40 GOTO 20
Happy to see "colour" spelled the English way. :-)What are the names of these early 2000's style forums? I would like to join them too.
Of course, when we say they are field axioms we mean those properties hold true for the elements of the field. If you see those properties, they talk about distributivity over the elements of the field and additive inverses of the elements also belong to the field, so the distributivity automatically applies to additive inverses too.
After that with a little algebra, "product of additive inverses of two elements is equal to the product of the two elements" comes out as a result (not a definition).
Of course, by "product" we mean whatever * represents. It is not necessarily the multiplication operator we see in numbers.