Similar but not the same: various versions of ♣ do not coincide
Mirna Džamonja, Saharon Shelah · Journal of Symbolic Logic · 1999
Abstract We consider various versions of the ♣ principle. This principle is a known consequence of ◊. It is well known that ◊ is not sensitive to minor changes in its definition, e.g., changing the guessing requirement form “guessing exactly” to “guessing modulo a finite set”. We show however, that this is not true for ♣. We consider some other variants of ♣ as well.