Nuprl Lemma : face-lattice-le
∀T:Type. ∀eq:EqDecider(T). ∀x,y:Point(face-lattice(T;eq)).
  (x ≤ y ⇐⇒ ∀s:fset(T + T). (s ∈ x ⇒ (↓∃t:fset(T + T). (t ∈ y ∧ t ⊆ s))))
Proof
Definitions occuring in Statement : 
face-lattice: face-lattice(T;eq), 
lattice-le: a ≤ b, 
lattice-point: Point(l), 
deq-fset: deq-fset(eq), 
f-subset: xs ⊆ ys, 
fset-member: a ∈ s, 
fset: fset(T), 
union-deq: union-deq(A;B;a;b), 
deq: EqDecider(T), 
all: ∀x:A. B[x], 
exists: ∃x:A. B[x], 
iff: P ⇐⇒ Q, 
squash: ↓T, 
implies: P ⇒ Q, 
and: P ∧ Q, 
union: left + right, 
universe: Type
Definitions unfolded in proof : 
all: ∀x:A. B[x], 
member: t ∈ T, 
uall: ∀[x:A]. B[x], 
top: Top, 
iff: P ⇐⇒ Q, 
and: P ∧ Q, 
implies: P ⇒ Q, 
guard: {T}, 
squash: ↓T, 
prop: ℙ, 
rev_implies: P ⇐ Q, 
exists: ∃x:A. B[x], 
subtype_rel: A ⊆r B, 
bdd-distributive-lattice: BoundedDistributiveLattice, 
so_lambda: λ2x.t[x], 
so_apply: x[s], 
uimplies: b supposing a, 
fset-ac-le: fset-ac-le(eq;ac1;ac2), 
sq_stable: SqStable(P), 
uiff: uiff(P;Q), 
rev_uimplies: rev_uimplies(P;Q), 
not: ¬A, 
cand: A c∧ B, 
false: False, 
fset-member: a ∈ s, 
assert: ↑b, 
ifthenelse: if b then t else f fi , 
deq-member: x ∈b L, 
reduce: reduce(f;k;as), 
list_ind: list_ind, 
empty-fset: {}, 
nil: [], 
it: ⋅, 
bfalse: ff
Lemmas referenced : 
face-lattice-le-1, 
fl-point-sq, 
istype-void, 
fset-ac-le-implies2, 
union-deq_wf, 
fset-member_wf, 
fset_wf, 
deq-fset_wf, 
fset-ac-le_wf, 
squash_wf, 
f-subset_wf, 
lattice-le_wf, 
face-lattice_wf, 
lattice-point_wf, 
subtype_rel_set, 
bounded-lattice-structure_wf, 
lattice-structure_wf, 
lattice-axioms_wf, 
bounded-lattice-structure-subtype, 
bounded-lattice-axioms_wf, 
uall_wf, 
equal_wf, 
lattice-meet_wf, 
lattice-join_wf, 
deq_wf, 
istype-universe, 
fset-all-iff, 
iff_weakening_uiff, 
fset-all_wf, 
bnot_wf, 
fset-null_wf, 
fset-filter_wf, 
deq-f-subset_wf, 
isect_wf, 
assert_wf, 
assert_witness, 
sq_stable__assert, 
assert_of_bnot, 
equal-wf-T-base, 
assert-fset-null, 
istype-assert, 
member-fset-filter, 
assert-deq-f-subset
Rules used in proof : 
cut, 
introduction, 
extract_by_obid, 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
lambdaFormation_alt, 
hypothesis, 
sqequalHypSubstitution, 
dependent_functionElimination, 
thin, 
hypothesisEquality, 
isectElimination, 
isect_memberEquality_alt, 
voidElimination, 
productElimination, 
independent_pairFormation, 
unionEquality, 
setElimination, 
rename, 
because_Cache, 
independent_functionElimination, 
imageElimination, 
sqequalRule, 
imageMemberEquality, 
baseClosed, 
universeIsType, 
functionIsType, 
productEquality, 
applyEquality, 
promote_hyp, 
inhabitedIsType, 
instantiate, 
lambdaEquality_alt, 
cumulativity, 
equalityTransitivity, 
equalitySymmetry, 
independent_isectElimination, 
universeEquality, 
isect_memberFormation_alt, 
isectIsTypeImplies, 
equalityIsType3, 
hyp_replacement, 
applyLambdaEquality
Latex:
\mforall{}T:Type.  \mforall{}eq:EqDecider(T).  \mforall{}x,y:Point(face-lattice(T;eq)).
    (x  \mleq{}  y  \mLeftarrow{}{}\mRightarrow{}  \mforall{}s:fset(T  +  T).  (s  \mmember{}  x  {}\mRightarrow{}  (\mdownarrow{}\mexists{}t:fset(T  +  T).  (t  \mmember{}  y  \mwedge{}  t  \msubseteq{}  s))))
Date html generated:
2019_10_31-AM-07_22_24
Last ObjectModification:
2018_11_10-PM-00_15_49
Theory : lattices
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