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Find R* isomorphic to A, for which R is in R*.
We shall replace each element rA Î | A | by the element r Î R ( = | R | ).
If we obtain an appropriate R* then, by isomorphism with A, there will be some b Î | R* | such that R* will satisfy S when v1 is replaced by b.
Include in R* the following:
i. R* = PRR* : the interpretation of PR in R*
ii. F* = fFR* : the interpretation of fF in R*
iii. r* = rR* = r
Notes
A. 1. R may be considered as a 1-place relation on R.
"xPRx is true in R, so it will be true in R*, so take R* as | R* |
2. R Ì R* so R is the restriction of R* to R.
3. R Ì R* so F is the restriction of F* to R.
B. 1. In what follows we apply - often implicitly - a method of showing that R* or F*
has some property that involves claiming:
1. R/F has that property;
2. The property can be expressed in L;
3. |=R f Û |=R* f
Ex. 1. The property <* on R*.
Ex. 2. The property of least upper boundedness.