We show, for any ordinal γ ≥ 3, that the class ℜaCAγ is pseudo-elementary and has a recursively enumerable elementary theory. ScK denotes the class of strong subalgebras of members of the class K. We devise games, Fn (3 ≤ n ≤ ω), G, H, and show, for an atomic relation algebra
with countably many atoms, that
![](//static-cambridge-org.ezproxyberklee.flo.org/content/id/urn%3Acambridge.org%3Aid%3Aarticle%3AS0022481200005417/resource/name/S0022481200005417_Uequ01.gif?pub-status=live)
for 3 ≤ n < ω. We use these games to show, for γ > 5 and any class K of relation algebras satisfying
![](//static-cambridge-org.ezproxyberklee.flo.org/content/id/urn%3Acambridge.org%3Aid%3Aarticle%3AS0022481200005417/resource/name/S0022481200005417_Uequ02.gif?pub-status=live)
that K is not closed under subalgebras and is not elementary. For infinite γ, the inclusion ℜaCAγ ⊂ ScℜaCAγ is strict.
For infinite γ and for a countable relation algebra
we show that
has a complete representation if and only if
is atomic and ∃ has a winning strategy in F (At(
)) if and only if
is atomic and
∈ ScℜaCAγ.