Nuprl Lemma : polymorphic-choice-sq
∀f:⋂A:Type. (A ⟶ A ⟶ A). ((f ~ λx.if f x is lambda then λy.x otherwise ⊥) ∨ (f ~ λx,y. y))
Proof
Definitions occuring in Statement : 
bottom: ⊥
, 
islambda: if z is lambda then a otherwise b
, 
all: ∀x:A. B[x]
, 
or: P ∨ Q
, 
apply: f a
, 
lambda: λx.A[x]
, 
isect: ⋂x:A. B[x]
, 
function: x:A ⟶ B[x]
, 
universe: Type
, 
sqequal: s ~ t
Definitions unfolded in proof : 
member: t ∈ T
, 
uall: ∀[x:A]. B[x]
, 
all: ∀x:A. B[x]
, 
implies: P 
⇒ Q
, 
or: P ∨ Q
, 
subtype_rel: A ⊆r B
, 
guard: {T}
, 
nat: ℕ
, 
le: A ≤ B
, 
and: P ∧ Q
, 
less_than': less_than'(a;b)
, 
false: False
, 
not: ¬A
, 
prop: ℙ
, 
top: Top
, 
uimplies: b supposing a
, 
so_lambda: λ2x.t[x]
, 
so_apply: x[s]
, 
has-value: (a)↓
, 
btrue: tt
, 
it: ⋅
, 
bfalse: ff
, 
ge: i ≥ j 
, 
exists: ∃x:A. B[x]
, 
satisfiable_int_formula: satisfiable_int_formula(fmla)
, 
decidable: Dec(P)
, 
squash: ↓T
, 
iff: P 
⇐⇒ Q
, 
rev_implies: P 
⇐ Q
, 
true: True
, 
sq_type: SQType(T)
Lemmas referenced : 
istype-universe, 
polymorphic-choice-base-sq, 
nat_wf, 
false_wf, 
le_wf, 
top_wf, 
value-type-has-value, 
set-value-type, 
int-value-type, 
has-value_wf_base, 
is-exception_wf, 
set_subtype_base, 
int_subtype_base, 
equal_wf, 
strictness-apply, 
bottom_diverge, 
int_term_value_var_lemma, 
int_formula_prop_and_lemma, 
itermVar_wf, 
intformand_wf, 
nat_properties, 
istype-le, 
int_formula_prop_wf, 
int_term_value_constant_lemma, 
int_formula_prop_le_lemma, 
istype-void, 
int_formula_prop_not_lemma, 
istype-int, 
itermConstant_wf, 
intformle_wf, 
intformnot_wf, 
full-omega-unsat, 
decidable__le, 
equal_functionality_wrt_subtype_rel2, 
istype-top, 
decidable__equal_int, 
intformeq_wf, 
int_formula_prop_eq_lemma, 
true_wf, 
squash_wf, 
member_wf, 
istype-sqequal, 
not_zero_sqequal_one, 
iff_weakening_equal, 
subtype_rel_self, 
istype-base, 
subtype_base_sq, 
equal-wf-base, 
or_wf, 
sqequal-wf-base
Rules used in proof : 
because_Cache, 
hypothesisEquality, 
Error :universeIsType, 
Error :functionIsType, 
hypothesis, 
universeEquality, 
thin, 
isectElimination, 
sqequalHypSubstitution, 
extract_by_obid, 
introduction, 
instantiate, 
cut, 
Error :isectIsType, 
Error :lambdaFormation_alt, 
sqequalReflexivity, 
computationStep, 
sqequalTransitivity, 
sqequalSubstitution, 
pointwiseFunctionality, 
dependent_functionElimination, 
independent_functionElimination, 
equalityTransitivity, 
equalitySymmetry, 
unionElimination, 
sqequalRule, 
applyEquality, 
lambdaEquality, 
isectEquality, 
cumulativity, 
functionEquality, 
dependent_set_memberEquality, 
natural_numberEquality, 
independent_pairFormation, 
lambdaFormation, 
islambdaCases, 
isect_memberFormation, 
axiomSqEquality, 
isect_memberEquality, 
voidElimination, 
voidEquality, 
independent_isectElimination, 
intEquality, 
functionExtensionality, 
callbyvalueApply, 
divergentSqle, 
baseClosed, 
baseApply, 
closedConclusion, 
inlEquality, 
sqequalIntensionalEquality, 
inrEquality, 
Error :equalityIstype, 
int_eqEquality, 
rename, 
setElimination, 
applyLambdaEquality, 
Error :isect_memberEquality_alt, 
Error :dependent_pairFormation_alt, 
approximateComputation, 
Error :dependent_set_memberEquality_alt, 
Error :inhabitedIsType, 
Error :lambdaEquality_alt, 
Error :isectIsTypeImplies, 
Error :isect_memberFormation_alt, 
int_eqReduceTrueSq, 
imageMemberEquality, 
imageElimination, 
unionEquality, 
sqequalExtensionalEquality, 
Error :inlEquality_alt, 
productElimination, 
callbyvalueIslambda
Latex:
\mforall{}f:\mcap{}A:Type.  (A  {}\mrightarrow{}  A  {}\mrightarrow{}  A).  ((f  \msim{}  \mlambda{}x.if  f  x  is  lambda  then  \mlambda{}y.x  otherwise  \mbot{})  \mvee{}  (f  \msim{}  \mlambda{}x,y.  y))
Date html generated:
2019_06_20-PM-02_45_22
Last ObjectModification:
2019_01_09-PM-03_39_35
Theory : num_thy_1
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