Section STABILITY.
Variable CS: compspecs.
Variables Delta Delta': tycontext.
Hypothesis extends: tycontext_sub Delta Delta'.

Lemma tc_bool_e_sub: forall b b' err rho phi,
(b = true -> b' = true) ->
denote_tc_assert (tc_bool b err) rho phi ->
denote_tc_assert (tc_bool b' err) rho phi.