First-Order Logic with Fleeing Indices
Löwenheim proved his well-known theorem for formulas of a standard first-order language with equality within a language extended with fleeing terms. He did not pay particular attention to this extended language; nor did Schröder, who, in a way, was the first to make use of fleeing indices. The aim of this appendix is to present a first-order language with fleeing terms appropriate for reconstructing, as far as is possible, the argument with which Löwenheim proved the theorem that today bears his name.
I do not intend to present all the peculiarities of the language of the logic of relatives with fleeing indices. I have slightly modified the notation and syntax in order to bring ...