>>271-273
>ものはいいよう

ID:xHuchH0kは、御大か
巡回ご苦労さまです

たしかに、ものはいいようだ

1）自然数を集めた集合Ｎの認識があり その性質を、ペアノが公理的に整理したのです（下記）
2）実数の概念も同様に、有理コーシー列の収束先で定義される以前から 認識は存在していた
　解析学などを通じて。Cantorは、それを精密化したのです（下記）

(参考)
https://en.wikipedia.org/wiki/Peano_axioms
Peano axioms
Historical second-order formulation
When Peano formulated his axioms, the language of mathematical logic was in its infancy.
The system of logical notation he created to present the axioms did not prove to be popular, although it was the genesis of the modern notation for set membership (∈, which comes from Peano's ε). Peano maintained a clear distinction between mathematical and logical symbols, which was not yet common in mathematics; such a separation had first been introduced in the Begriffsschrift by Gottlob Frege, published in 1879.[7] Peano was unaware of Frege's work and independently recreated his logical apparatus based on the work of Boole and Schröder.[8]
The Peano axioms define the arithmetical properties of natural numbers, usually represented as a set N or
Ｎ.

https://en.wikipedia.org/wiki/Georg_Cantor
Georg Cantor
Mathematical work
Cantor's work between 1874 and 1884 is the origin of set theory.[39]
Prior to this work, the concept of a set was a rather elementary one that had been used implicitly since the beginning of mathematics, dating back to the ideas of Aristotle.