Nuprl Lemma : es-first-exists
0,22
postcript
pdf
es
:ES,
e'
:E.
e
:E. first(
e
) &
e
e'
latex
Definitions
Trans
x
,
y
:
T
.
E
(
x
;
y
)
,
pred(
e
)
,
Dec(
P
)
,
P
Q
,
ES
,
WellFnd{i}(
A
;
x
,
y
.
R
(
x
;
y
))
,
x
.
t
(
x
)
,
{
T
}
,
P
Q
,
(
e
<loc
e'
)
,
x
:
A
.
B
(
x
)
,
E
,
P
&
Q
,
Prop
,
b
,
first(
e
)
,
t
T
,
e
e'
,
x
:
A
.
B
(
x
)
Lemmas
es-le
wf
,
es-first
wf
,
assert
wf
,
es-locl
wf
,
es-E
wf
,
es-locl-wellfnd
,
event
system
wf
,
decidable
assert
,
es-pred
wf
,
es-pred-locl
,
es-le-trans
origin
es:ES, e':E. 
e:E. first(e) & e 
e' es:ES, e':E. e:E. first(e) & e e' 
Q
x. t(x)
Qx:A. B(x)
b
T e' x:A. B(x)