Nuprl Lemma : strong-subtype-union
11,40
postcript
pdf
A
,
B
,
C
,
D
:Type. strong-subtype(
A
;
C
)
strong-subtype(
B
;
D
)
strong-subtype(
A
+
B
;
C
+
D
)
latex
Definitions
x
:
A
.
B
(
x
)
,
P
Q
,
strong-subtype(
A
;
B
)
,
A
c
B
,
S
T
,
t
T
,
x
:
A
.
B
(
x
)
,
Lemmas
strong-subtype
wf
origin
A, B, C, D:Type. strong-subtype(A;C) 
strong-subtype(B;D) strong-subtype(A + B;C + D) A, B, C, D:Type. strong-subtype(A;C) strong-subtype(B;D) strong-subtype(A + B;C + D) x:A. B(x) Q
B
T
T
x:A. B(x)