DEFINITION csubt_getl_abbr()
TYPE =
       ∀g:G
         .∀c1:C
           .∀d1:C
             .∀u:T
               .∀n:nat
                 .getl n c1 (CHead d1 (Bind Abbr) u)
                   →∀c2:C
                        .csubt g c1 c2
                          →ex2 C λd2:C.csubt g d1 d2 λd2:C.getl n c2 (CHead d2 (Bind Abbr) u)
BODY =
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