My understanding is that it stands for "founded relation", as in well-founded but without the "well", I think because it doesn't have any other ordering properties like being a partial order attached to it.
On Wed, May 1, 2024 at 5:21 AM 'B. Wilson' via Metamath < metamath@googlegroups.com> wrote: > This has been bugging me midly for a while, but I couldn't figure out what > the > Fr symbol in df-fr stood for: > > 19201 df-fr $a |- ( R Fr A <-> A. x ( ( x C_ A /\ x =/= (/) ) -> E. y > e. x A. z e. x -. z R y ) ) $. > > I finally bothered to look up the Takeuti and Zaring reference, which also > uses > "Fr" and calls R a "foundational relation". It's not super important, but > would > it be worth mentioning this in df-fr's comment? > > Cheers, > B. Wilson > > -- > You received this message because you are subscribed to the Google Groups > "Metamath" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to metamath+unsubscr...@googlegroups.com. > To view this discussion on the web visit > https://groups.google.com/d/msgid/metamath/2F5KIFFJJY2KH.28Z6N87TP90O2%40wilsonb.com > . > -- You received this message because you are subscribed to the Google Groups "Metamath" group. To unsubscribe from this group and stop receiving emails from it, send an email to metamath+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/metamath/CAFXXJSsXfJqj3nGxjuDEFGCMAw8Zvq6AFF0wZ53qib3d8u%3DD3A%40mail.gmail.com.