Nuprl Lemma : get_face-wf
∀[X:CubicalSet]. ∀[I,J:Cname List]. ∀[x:nameset(I)]. ∀[i:ℕ2]. ∀[box:open_box(X;I;J;x;i)].
  (get_face(x;i;box) ∈ {f:I-face(X;I)| (f ∈ box) ∧ (face-name(f) = <x, i> ∈ (nameset(I) × ℕ2))} )
Proof
Definitions occuring in Statement : 
get_face: get_face(y;c;box), 
open_box: open_box(X;I;J;x;i), 
face-name: face-name(f), 
I-face: I-face(X;I), 
cubical-set: CubicalSet, 
nameset: nameset(L), 
coordinate_name: Cname, 
l_member: (x ∈ l), 
list: T List, 
int_seg: {i..j-}, 
uall: ∀[x:A]. B[x], 
and: P ∧ Q, 
member: t ∈ T, 
set: {x:A| B[x]} , 
pair: <a, b>, 
product: x:A × B[x], 
natural_number: $n, 
equal: s = t ∈ T
Definitions unfolded in proof : 
uall: ∀[x:A]. B[x], 
member: t ∈ T, 
open_box: open_box(X;I;J;x;i), 
and: P ∧ Q, 
cand: A c∧ B, 
get_face: get_face(y;c;box), 
prop: ℙ, 
all: ∀x:A. B[x], 
I-face: I-face(X;I), 
pi1: fst(t), 
nameset: nameset(L), 
coordinate_name: Cname, 
int_upper: {i...}, 
implies: P ⇒ Q, 
bool: 𝔹, 
unit: Unit, 
it: ⋅, 
btrue: tt, 
band: p ∧b q, 
ifthenelse: if b then t else f fi , 
uiff: uiff(P;Q), 
uimplies: b supposing a, 
pi2: snd(t), 
int_seg: {i..j-}, 
bfalse: ff, 
subtype_rel: A ⊆r B, 
face-name: face-name(f), 
iff: P ⇐⇒ Q, 
rev_implies: P ⇐ Q, 
guard: {T}, 
lelt: i ≤ j < k, 
decidable: Dec(P), 
or: P ∨ Q, 
satisfiable_int_formula: satisfiable_int_formula(fmla), 
exists: ∃x:A. B[x], 
false: False, 
not: ¬A, 
top: Top, 
sq_stable: SqStable(P), 
squash: ↓T, 
sq_type: SQType(T), 
so_lambda: λ2x.t[x], 
so_apply: x[s], 
cons: [a / b], 
l_exists: (∃x∈L. P[x]), 
l_all: (∀x∈L.P[x]), 
less_than: a < b
Lemmas referenced : 
filter_type, 
I-face_wf, 
l_member_wf, 
eq_int_wf, 
bool_wf, 
eqtt_to_assert, 
assert_of_eq_int, 
equal_wf, 
list-subtype, 
list_wf, 
assert_wf, 
hd_wf, 
face-name_wf, 
open_box_wf, 
int_seg_wf, 
nameset_wf, 
coordinate_name_wf, 
cubical-set_wf, 
subtype_rel_list, 
band_wf, 
iff_transitivity, 
iff_weakening_uiff, 
assert_of_band, 
int_seg_properties, 
decidable__equal_int, 
satisfiable-full-omega-tt, 
intformand_wf, 
intformnot_wf, 
intformeq_wf, 
itermVar_wf, 
int_formula_prop_and_lemma, 
int_formula_prop_not_lemma, 
int_formula_prop_eq_lemma, 
int_term_value_var_lemma, 
int_formula_prop_wf, 
sq_stable__l_member, 
decidable__equal-coordinate_name, 
sq_stable__le, 
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, 
subtype_base_sq, 
int_subtype_base, 
set_wf, 
list-cases, 
product_subtype_list, 
sqequal-nil, 
nil_wf, 
filter_is_nil_implies, 
select_wf, 
length_wf, 
pi1_wf_top, 
set_subtype_base, 
nameset_subtype_base, 
length_cons_ge_one, 
top_wf
Rules used in proof : 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
isect_memberFormation, 
cut, 
sqequalHypSubstitution, 
setElimination, 
thin, 
rename, 
productElimination, 
introduction, 
extract_by_obid, 
isectElimination, 
setEquality, 
hypothesisEquality, 
hypothesis, 
lambdaEquality, 
lambdaFormation, 
sqequalRule, 
unionElimination, 
equalityElimination, 
independent_isectElimination, 
because_Cache, 
equalityTransitivity, 
equalitySymmetry, 
dependent_functionElimination, 
independent_functionElimination, 
productEquality, 
independent_pairEquality, 
natural_numberEquality, 
applyEquality, 
dependent_set_memberEquality, 
independent_pairFormation, 
intEquality, 
dependent_pairFormation, 
int_eqEquality, 
isect_memberEquality, 
voidElimination, 
voidEquality, 
computeAll, 
imageMemberEquality, 
baseClosed, 
imageElimination, 
instantiate, 
cumulativity, 
promote_hyp, 
hypothesis_subsumption, 
applyLambdaEquality
Latex:
\mforall{}[X:CubicalSet].  \mforall{}[I,J:Cname  List].  \mforall{}[x:nameset(I)].  \mforall{}[i:\mBbbN{}2].  \mforall{}[box:open\_box(X;I;J;x;i)].
    (get\_face(x;i;box)  \mmember{}  \{f:I-face(X;I)|  (f  \mmember{}  box)  \mwedge{}  (face-name(f)  =  <x,  i>)\}  )
Date html generated:
2017_10_05-AM-10_21_03
Last ObjectModification:
2017_07_28-AM-11_21_11
Theory : cubical!sets
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