Nuprl Lemma : hd_wf
11,40
postcript
pdf
A
:Type,
l
:(
A
List). ge(||
l
||; 1)
(hd(
l
)
A
)
latex
Definitions
t
T
,
P
Q
,
x
:
A
.
B
(
x
)
,
hd(
l
)
,
False
,
A
,
A
B
,
Y
,
||
as
||
,
ge(
i
;
j
)
,
prop{i:l}
Lemmas
length
wf1
,
ge
wf
,
length
wf2
origin
A:Type, l:(A List). ge(||l||; 1) 
(hd(l) 
A) A:Type, l:(A List). ge(||l||; 1) (hd(l) A) T Qx:A. B(x)
A
B