Nuprl Lemma : same-face-square-commutes
∀[C:SmallCategory]. ∀[I:Cname List]. ∀[J:nameset(I) List].
  ∀[x:nameset(I)]. ∀[i:ℕ2]. ∀[box:open_box(cubical-nerve(C);I;J;x;i)]. ∀[f,g,h,k:name-morph(I;[])].
    ∀a,b:nameset(I).
      nerve_box_edge(box;f;a) o nerve_box_edge(box;g;b) = nerve_box_edge(box;f;b) o nerve_box_edge(box;h;a) 
      supposing (((¬(a = b ∈ nameset(I))) ∧ ((f a) = 0 ∈ ℕ2))
      ∧ ((f b) = 0 ∈ ℕ2)
      ∧ (g = flip(f;a) ∈ name-morph(I;[]))
      ∧ (h = flip(f;b) ∈ name-morph(I;[]))
      ∧ (k = flip(flip(f;a);b) ∈ name-morph(I;[])))
      ∧ (∃v:I-face(cubical-nerve(C);I)
          ((v ∈ box)
          ∧ (¬(dimension(v) = b ∈ Cname))
          ∧ (¬(dimension(v) = a ∈ Cname))
          ∧ (direction(v) = (f dimension(v)) ∈ ℕ2))) 
  supposing (∃j1∈J. (∃j2∈J. ¬(j1 = j2 ∈ Cname)))
Proof
Definitions occuring in Statement : 
nerve_box_edge: nerve_box_edge(box;c;y), 
nerve_box_label: nerve_box_label(box;L), 
cubical-nerve: cubical-nerve(X), 
open_box: open_box(X;I;J;x;i), 
face-direction: direction(f), 
face-dimension: dimension(f), 
I-face: I-face(X;I), 
name-morph-flip: flip(f;y), 
name-morph: name-morph(I;J), 
nameset: nameset(L), 
coordinate_name: Cname, 
cat-square-commutes: x_y1 o y1_z = x_y2 o y2_z, 
small-category: SmallCategory, 
l_exists: (∃x∈L. P[x]), 
l_member: (x ∈ l), 
nil: [], 
list: T List, 
int_seg: {i..j-}, 
uimplies: b supposing a, 
uall: ∀[x:A]. B[x], 
all: ∀x:A. B[x], 
exists: ∃x:A. B[x], 
not: ¬A, 
and: P ∧ Q, 
apply: f a, 
natural_number: $n, 
equal: s = t ∈ T
Definitions unfolded in proof : 
uall: ∀[x:A]. B[x], 
member: t ∈ T, 
uimplies: b supposing a, 
all: ∀x:A. B[x], 
and: P ∧ Q, 
cand: A c∧ B, 
or: P ∨ Q, 
l_exists: (∃x∈L. P[x]), 
exists: ∃x:A. B[x], 
select: L[n], 
nil: [], 
it: ⋅, 
so_lambda: λ2x y.t[x; y], 
top: Top, 
so_apply: x[s1;s2], 
assert: ↑b, 
ifthenelse: if b then t else f fi , 
btrue: tt, 
guard: {T}, 
int_seg: {i..j-}, 
lelt: i ≤ j < k, 
nameset: nameset(L), 
false: False, 
coordinate_name: Cname, 
int_upper: {i...}, 
satisfiable_int_formula: satisfiable_int_formula(fmla), 
implies: P ⇒ Q, 
not: ¬A, 
prop: ℙ, 
cons: [a / b], 
bfalse: ff, 
cat-square-commutes: x_y1 o y1_z = x_y2 o y2_z, 
so_lambda: λ2x.t[x], 
open_box: open_box(X;I;J;x;i), 
subtype_rel: A ⊆r B, 
name-morph: name-morph(I;J), 
so_apply: x[s], 
name-morph-flip: flip(f;y), 
uiff: uiff(P;Q), 
iff: P ⇐⇒ Q, 
rev_implies: P ⇐ Q, 
sq_type: SQType(T), 
bool: 𝔹, 
unit: Unit, 
bnot: ¬bb, 
squash: ↓T, 
true: True, 
decidable: Dec(P)
Lemmas referenced : 
same-face-edge-arrows-commute3, 
nameset_wf, 
list-cases, 
stuck-spread, 
base_wf, 
length_of_nil_lemma, 
null_nil_lemma, 
int_seg_properties, 
satisfiable-full-omega-tt, 
intformand_wf, 
intformless_wf, 
itermVar_wf, 
itermConstant_wf, 
intformle_wf, 
int_formula_prop_and_lemma, 
int_formula_prop_less_lemma, 
int_term_value_var_lemma, 
int_term_value_constant_lemma, 
int_formula_prop_le_lemma, 
int_formula_prop_wf, 
product_subtype_list, 
null_cons_lemma, 
false_wf, 
not_wf, 
equal_wf, 
equal-wf-T-base, 
name-morph_wf, 
nil_wf, 
coordinate_name_wf, 
name-morph-flip_wf, 
exists_wf, 
I-face_wf, 
cubical-nerve_wf, 
l_member_wf, 
face-dimension_wf, 
int_seg_wf, 
face-direction_wf, 
open_box_wf, 
subtype_rel_list, 
l_exists_wf, 
list_wf, 
small-category_wf, 
subtype_base_sq, 
bool_wf, 
bool_subtype_base, 
eqff_to_assert, 
eq-cname_wf, 
iff_transitivity, 
assert_wf, 
bnot_wf, 
iff_weakening_uiff, 
assert_of_bnot, 
assert-eq-cname, 
set_subtype_base, 
le_wf, 
int_subtype_base, 
extd-nameset-nil, 
eqtt_to_assert, 
bool_cases_sqequal, 
assert-bnot, 
squash_wf, 
true_wf, 
cat-arrow_wf, 
nerve_box_label_wf, 
decidable__assert, 
null_wf3, 
top_wf, 
or_wf, 
cat-comp_wf, 
nerve_box_edge_wf, 
subtype_rel-equal, 
iff_weakening_equal, 
set_wf, 
cat-ob_wf, 
name-morph-flips-commute
Rules used in proof : 
cut, 
introduction, 
extract_by_obid, 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
isect_memberFormation, 
hypothesis, 
sqequalHypSubstitution, 
isectElimination, 
thin, 
hypothesisEquality, 
independent_isectElimination, 
dependent_functionElimination, 
lambdaFormation, 
productElimination, 
independent_pairFormation, 
unionElimination, 
sqequalRule, 
baseClosed, 
isect_memberEquality, 
voidElimination, 
voidEquality, 
natural_numberEquality, 
equalityTransitivity, 
equalitySymmetry, 
applyLambdaEquality, 
setElimination, 
rename, 
dependent_pairFormation, 
lambdaEquality, 
int_eqEquality, 
intEquality, 
computeAll, 
promote_hyp, 
hypothesis_subsumption, 
independent_functionElimination, 
hyp_replacement, 
comment, 
axiomEquality, 
productEquality, 
because_Cache, 
applyEquality, 
setEquality, 
dependent_set_memberEquality, 
instantiate, 
cumulativity, 
impliesFunctionality, 
equalityElimination, 
imageElimination, 
universeEquality, 
imageMemberEquality, 
inlFormation, 
inrFormation
Latex:
\mforall{}[C:SmallCategory].  \mforall{}[I:Cname  List].  \mforall{}[J:nameset(I)  List].
    \mforall{}[x:nameset(I)].  \mforall{}[i:\mBbbN{}2].  \mforall{}[box:open\_box(cubical-nerve(C);I;J;x;i)].  \mforall{}[f,g,h,k:name-morph(I;[])].
        \mforall{}a,b:nameset(I).
            nerve\_box\_edge(box;f;a)  o  nerve\_box\_edge(box;g;b)
            =  nerve\_box\_edge(box;f;b)  o  nerve\_box\_edge(box;h;a)  
            supposing  (((\mneg{}(a  =  b))  \mwedge{}  ((f  a)  =  0))
            \mwedge{}  ((f  b)  =  0)
            \mwedge{}  (g  =  flip(f;a))
            \mwedge{}  (h  =  flip(f;b))
            \mwedge{}  (k  =  flip(flip(f;a);b)))
            \mwedge{}  (\mexists{}v:I-face(cubical-nerve(C);I)
                    ((v  \mmember{}  box)
                    \mwedge{}  (\mneg{}(dimension(v)  =  b))
                    \mwedge{}  (\mneg{}(dimension(v)  =  a))
                    \mwedge{}  (direction(v)  =  (f  dimension(v)))))  
    supposing  (\mexists{}j1\mmember{}J.  (\mexists{}j2\mmember{}J.  \mneg{}(j1  =  j2)))
 Date html generated: 
2017_10_05-PM-03_39_28
 Last ObjectModification: 
2017_07_28-AM-11_26_21
Theory : cubical!sets
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