Section UnpackStratifiedSemanticsWithSeparation.
Context
{W V G S' U F world_erase VU GF A projA H HG}
`{SSS : StratifiedSemanticsWithSeparation W V G S' U F world_erase VU GF A projA H HG}.

Lemma HG_wellformed : forall h g,
HG h g
-> H h /\ G g.