Nuprl Lemma : oob-getleft_wf
∀[B,A:Type]. ∀[x:{x:one_or_both(A;B)| ↑oob-hasleft(x)} ].  (oob-getleft(x) ∈ A)
Proof
Definitions occuring in Statement : 
oob-getleft: oob-getleft(x)
, 
oob-hasleft: oob-hasleft(x)
, 
one_or_both: one_or_both(A;B)
, 
assert: ↑b
, 
uall: ∀[x:A]. B[x]
, 
member: t ∈ T
, 
set: {x:A| B[x]} 
, 
universe: Type
Definitions unfolded in proof : 
uall: ∀[x:A]. B[x]
, 
member: t ∈ T
, 
oob-getleft: oob-getleft(x)
, 
all: ∀x:A. B[x]
, 
implies: P 
⇒ Q
, 
bool: 𝔹
, 
unit: Unit
, 
it: ⋅
, 
btrue: tt
, 
uiff: uiff(P;Q)
, 
and: P ∧ Q
, 
uimplies: b supposing a
, 
ifthenelse: if b then t else f fi 
, 
bfalse: ff
, 
subtype_rel: A ⊆r B
, 
top: Top
, 
prop: ℙ
, 
so_lambda: λ2x.t[x]
, 
so_apply: x[s]
, 
oob-hasleft: oob-hasleft(x)
, 
or: P ∨ Q
, 
not: ¬A
, 
false: False
Lemmas referenced : 
oobleft?_wf, 
bool_wf, 
eqtt_to_assert, 
oobleft-lval_wf, 
uiff_transitivity, 
equal-wf-T-base, 
assert_wf, 
bnot_wf, 
not_wf, 
eqff_to_assert, 
assert_of_bnot, 
pi1_wf_top, 
oobboth-bval_wf, 
top_wf, 
oob-subtype, 
equal_wf, 
set_wf, 
one_or_both_wf, 
oob-hasleft_wf, 
assert_of_bor, 
oobboth?_wf
Rules used in proof : 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
isect_memberFormation, 
introduction, 
cut, 
setElimination, 
thin, 
rename, 
sqequalRule, 
extract_by_obid, 
sqequalHypSubstitution, 
isectElimination, 
cumulativity, 
hypothesisEquality, 
hypothesis, 
lambdaFormation, 
unionElimination, 
equalityElimination, 
because_Cache, 
productElimination, 
independent_isectElimination, 
equalityTransitivity, 
equalitySymmetry, 
baseClosed, 
independent_functionElimination, 
applyEquality, 
lambdaEquality, 
isect_memberEquality, 
voidElimination, 
voidEquality, 
dependent_functionElimination, 
axiomEquality, 
universeEquality
Latex:
\mforall{}[B,A:Type].  \mforall{}[x:\{x:one\_or\_both(A;B)|  \muparrow{}oob-hasleft(x)\}  ].    (oob-getleft(x)  \mmember{}  A)
Date html generated:
2018_05_21-PM-08_00_02
Last ObjectModification:
2017_07_26-PM-05_36_53
Theory : general
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