Common Notion One

Things which equal the same thing equal each other.

  • a = 2.1
  • b = 2.1

therefore, a=b.

Another interesting outcome:

variable ‘a’ is equal to something. Elsewhere, another copy of ‘a’ is also equal to that same thing.

Therefore, the first a equals the second a.

a=a

This is the axiom of Reflexivity.