Nuprl Lemma : funinv-funinv
∀[n:ℕ]. ∀[f:{f:ℕn ⟶ ℕn| Inj(ℕn;ℕn;f)} ].  (inv(inv(f)) = f ∈ {f:ℕn ⟶ ℕn| Inj(ℕn;ℕn;f)} )
Proof
Definitions occuring in Statement : 
funinv: inv(f)
, 
inject: Inj(A;B;f)
, 
int_seg: {i..j-}
, 
nat: ℕ
, 
uall: ∀[x:A]. B[x]
, 
set: {x:A| B[x]} 
, 
function: x:A ⟶ B[x]
, 
natural_number: $n
, 
equal: s = t ∈ T
Definitions unfolded in proof : 
uall: ∀[x:A]. B[x]
, 
member: t ∈ T
, 
squash: ↓T
, 
nat: ℕ
, 
prop: ℙ
, 
so_lambda: λ2x.t[x]
, 
so_apply: x[s]
, 
inject: Inj(A;B;f)
, 
all: ∀x:A. B[x]
, 
subtype_rel: A ⊆r B
, 
implies: P 
⇒ Q
, 
and: P ∧ Q
, 
guard: {T}
, 
int_seg: {i..j-}
, 
lelt: i ≤ j < k
, 
ge: i ≥ j 
, 
decidable: Dec(P)
, 
or: P ∨ Q
, 
uimplies: b supposing a
, 
satisfiable_int_formula: satisfiable_int_formula(fmla)
, 
exists: ∃x:A. B[x]
, 
false: False
, 
not: ¬A
, 
top: Top
Lemmas referenced : 
int_formula_prop_less_lemma, 
intformless_wf, 
decidable__lt, 
int_term_value_constant_lemma, 
int_formula_prop_le_lemma, 
itermConstant_wf, 
intformle_wf, 
decidable__le, 
int_formula_prop_wf, 
int_term_value_var_lemma, 
int_formula_prop_eq_lemma, 
int_formula_prop_not_lemma, 
int_formula_prop_and_lemma, 
itermVar_wf, 
intformeq_wf, 
intformnot_wf, 
intformand_wf, 
satisfiable-full-omega-tt, 
decidable__equal_int, 
nat_properties, 
lelt_wf, 
int_seg_properties, 
funinv-property, 
nat_wf, 
set_wf, 
inject_wf, 
int_seg_wf, 
funinv_wf2
Rules used in proof : 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
isect_memberFormation, 
introduction, 
cut, 
lemma_by_obid, 
sqequalHypSubstitution, 
isectElimination, 
thin, 
hypothesisEquality, 
hypothesis, 
applyEquality, 
lambdaEquality, 
setElimination, 
rename, 
sqequalRule, 
imageMemberEquality, 
baseClosed, 
setEquality, 
functionEquality, 
natural_numberEquality, 
imageElimination, 
dependent_set_memberEquality, 
functionExtensionality, 
isect_memberEquality, 
axiomEquality, 
because_Cache, 
dependent_functionElimination, 
independent_functionElimination, 
equalityTransitivity, 
equalitySymmetry, 
productElimination, 
intEquality, 
unionElimination, 
independent_isectElimination, 
dependent_pairFormation, 
int_eqEquality, 
voidElimination, 
voidEquality, 
independent_pairFormation, 
computeAll
Latex:
\mforall{}[n:\mBbbN{}].  \mforall{}[f:\{f:\mBbbN{}n  {}\mrightarrow{}  \mBbbN{}n|  Inj(\mBbbN{}n;\mBbbN{}n;f)\}  ].    (inv(inv(f))  =  f)
Date html generated:
2016_05_14-AM-07_30_51
Last ObjectModification:
2016_01_14-PM-10_01_36
Theory : int_2
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