Nuprl Lemma : fact_wf
∀[n:ℕ]. ((n)! ∈ ℕ+)
Proof
Definitions occuring in Statement : 
fact: (n)!, 
nat_plus: ℕ+, 
nat: ℕ, 
uall: ∀[x:A]. B[x], 
member: t ∈ T
Definitions unfolded in proof : 
uall: ∀[x:A]. B[x], 
member: t ∈ T, 
nat: ℕ, 
implies: P ⇒ Q, 
false: False, 
ge: i ≥ j , 
uimplies: b supposing a, 
not: ¬A, 
satisfiable_int_formula: satisfiable_int_formula(fmla), 
exists: ∃x:A. B[x], 
all: ∀x:A. B[x], 
top: Top, 
and: P ∧ Q, 
prop: ℙ, 
lt_int: i <z j, 
subtract: n - m, 
ifthenelse: if b then t else f fi , 
btrue: tt, 
nat_plus: ℕ+, 
less_than: a < b, 
squash: ↓T, 
less_than': less_than'(a;b), 
true: True, 
bool: 𝔹, 
unit: Unit, 
it: ⋅, 
uiff: uiff(P;Q), 
guard: {T}, 
bfalse: ff, 
subtype_rel: A ⊆r B, 
or: P ∨ Q, 
sq_type: SQType(T), 
bnot: ¬bb, 
assert: ↑b, 
rev_implies: P ⇐ Q, 
iff: P ⇐⇒ Q
Lemmas referenced : 
nat_properties, 
full-omega-unsat, 
intformand_wf, 
intformle_wf, 
itermConstant_wf, 
itermVar_wf, 
intformless_wf, 
istype-int, 
int_formula_prop_and_lemma, 
istype-void, 
int_formula_prop_le_lemma, 
int_term_value_constant_lemma, 
int_term_value_var_lemma, 
int_formula_prop_less_lemma, 
int_formula_prop_wf, 
ge_wf, 
less_than_wf, 
fact_unroll, 
subtract-1-ge-0, 
lt_int_wf, 
eqtt_to_assert, 
assert_of_lt_int, 
nat_plus_properties, 
eqff_to_assert, 
int_subtype_base, 
bool_cases_sqequal, 
subtype_base_sq, 
bool_wf, 
bool_subtype_base, 
assert-bnot, 
iff_weakening_uiff, 
assert_wf, 
mul_nat_plus, 
nat_wf
Rules used in proof : 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
Error :isect_memberFormation_alt, 
introduction, 
cut, 
extract_by_obid, 
sqequalHypSubstitution, 
isectElimination, 
thin, 
hypothesisEquality, 
hypothesis, 
setElimination, 
rename, 
intWeakElimination, 
Error :lambdaFormation_alt, 
natural_numberEquality, 
independent_isectElimination, 
approximateComputation, 
independent_functionElimination, 
Error :dependent_pairFormation_alt, 
Error :lambdaEquality_alt, 
int_eqEquality, 
dependent_functionElimination, 
Error :isect_memberEquality_alt, 
voidElimination, 
sqequalRule, 
independent_pairFormation, 
Error :universeIsType, 
axiomEquality, 
equalityTransitivity, 
equalitySymmetry, 
Error :functionIsTypeImplies, 
Error :inhabitedIsType, 
Error :dependent_set_memberEquality_alt, 
imageMemberEquality, 
baseClosed, 
because_Cache, 
unionElimination, 
equalityElimination, 
productElimination, 
applyLambdaEquality, 
Error :equalityIsType2, 
baseApply, 
closedConclusion, 
applyEquality, 
promote_hyp, 
instantiate, 
cumulativity, 
Error :equalityIsType1
Latex:
\mforall{}[n:\mBbbN{}].  ((n)!  \mmember{}  \mBbbN{}\msupplus{})
Date html generated:
2019_06_20-PM-02_30_10
Last ObjectModification:
2018_10_05-PM-11_31_46
Theory : num_thy_1
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