Sandwich Principle/Linguistic Note
Linguistic Note on Sandwich Principle
As they explain, when $x \subset y \subset z$, we may consider $y$ to be sandwiched between $x$ and $z$.
Thus the Sandwich Principle tells us that, given the conditions constraining $x$, $y$ and $\map g x$, there can be no such $y$ sandwiched between $x$ and $\map g x$.
- 2010: Raymond M. Smullyan and Melvin Fitting: Set Theory and the Continuum Problem (revised ed.) ... (previous) ... (next): Chapter $3$: The Natural Numbers: $\S 4$ A double induction principle and its applications: Lemma $4.9$: Remarks