Nuprl Lemma : preserved_by_or
4,23
postcript
pdf
T
:Type,
P
:(
T
Prop),
R1
,
R2
:(
T
T
Prop).
R1
preserves
P
R2
preserves
P
R1
R2
preserves
P
latex
Definitions
R1
R2
,
R
preserves
P
,
Prop
,
t
T
,
P
Q
,
x
f
y
,
x
:
A
.
B
(
x
)
,
P
Q
origin
T:Type, P:(T
Prop), R1, R2:(TTProp).
R2 preserves P R1 
R2 preserves P T:Type, P:(TProp), R1, R2:(TTProp).
R2 preserves P R1 R2 preserves P R2
T Qx:A. B(x) Q