Nuprl Lemma : funinv_wf
∀[n,m:ℕ]. ∀[f:{f:ℕn ⟶ ℕm| Surj(ℕn;ℕm;f)} ].  (inv(f) ∈ {g:ℕm ⟶ ℕn| Inj(ℕm;ℕn;g) ∧ (∀x:ℕm. ((f (g x)) = x ∈ ℤ))} )
Proof
Definitions occuring in Statement : 
funinv: inv(f)
, 
surject: Surj(A;B;f)
, 
inject: Inj(A;B;f)
, 
int_seg: {i..j-}
, 
nat: ℕ
, 
uall: ∀[x:A]. B[x]
, 
all: ∀x:A. B[x]
, 
and: P ∧ Q
, 
member: t ∈ T
, 
set: {x:A| B[x]} 
, 
apply: f a
, 
function: x:A ⟶ B[x]
, 
natural_number: $n
, 
int: ℤ
, 
equal: s = t ∈ T
Definitions unfolded in proof : 
funinv: inv(f)
, 
so_apply: x[s]
, 
so_lambda: λ2x.t[x]
, 
uiff: uiff(P;Q)
, 
prop: ℙ
, 
top: Top
, 
false: False
, 
satisfiable_int_formula: satisfiable_int_formula(fmla)
, 
implies: P 
⇒ Q
, 
not: ¬A
, 
or: P ∨ Q
, 
decidable: Dec(P)
, 
and: P ∧ Q
, 
lelt: i ≤ j < k
, 
ge: i ≥ j 
, 
guard: {T}
, 
exists: ∃x:A. B[x]
, 
uimplies: b supposing a
, 
nat: ℕ
, 
int_seg: {i..j-}
, 
subtype_rel: A ⊆r B
, 
all: ∀x:A. B[x]
, 
surject: Surj(A;B;f)
, 
member: t ∈ T
, 
uall: ∀[x:A]. B[x]
, 
cand: A c∧ B
, 
inject: Inj(A;B;f)
Lemmas referenced : 
nat_wf, 
surject_wf, 
set_wf, 
exists_wf, 
assert_wf, 
assert_of_eq_int, 
equal_wf, 
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, 
full-omega-unsat, 
decidable__equal_int, 
nat_properties, 
int_seg_properties, 
int_seg_wf, 
eq_int_wf, 
mu-bound-property+, 
inject_wf, 
all_wf, 
decidable__le, 
intformle_wf, 
itermConstant_wf, 
int_formula_prop_le_lemma, 
int_term_value_constant_lemma, 
decidable__lt, 
intformless_wf, 
int_formula_prop_less_lemma, 
lelt_wf, 
and_wf
Rules used in proof : 
functionEquality, 
axiomEquality, 
cumulativity, 
addLevel, 
independent_pairFormation, 
voidEquality, 
voidElimination, 
isect_memberEquality, 
intEquality, 
int_eqEquality, 
independent_functionElimination, 
approximateComputation, 
unionElimination, 
applyLambdaEquality, 
equalitySymmetry, 
equalityTransitivity, 
dependent_pairFormation, 
productElimination, 
independent_isectElimination, 
natural_numberEquality, 
sqequalRule, 
because_Cache, 
applyEquality, 
lambdaEquality, 
isectElimination, 
extract_by_obid, 
hypothesisEquality, 
dependent_functionElimination, 
hypothesis, 
lambdaFormation, 
sqequalHypSubstitution, 
rename, 
thin, 
setElimination, 
cut, 
introduction, 
isect_memberFormation, 
sqequalReflexivity, 
computationStep, 
sqequalTransitivity, 
sqequalSubstitution, 
dependent_set_memberEquality, 
productEquality
Latex:
\mforall{}[n,m:\mBbbN{}].  \mforall{}[f:\{f:\mBbbN{}n  {}\mrightarrow{}  \mBbbN{}m|  Surj(\mBbbN{}n;\mBbbN{}m;f)\}  ].
    (inv(f)  \mmember{}  \{g:\mBbbN{}m  {}\mrightarrow{}  \mBbbN{}n|  Inj(\mBbbN{}m;\mBbbN{}n;g)  \mwedge{}  (\mforall{}x:\mBbbN{}m.  ((f  (g  x))  =  x))\}  )
Date html generated:
2019_06_20-PM-01_17_35
Last ObjectModification:
2018_08_25-AM-08_20_11
Theory : int_2
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