Nuprl Lemma : lattice-join-idempotent
∀[l:Lattice]. ∀[u:Point(l)].  (u ∨ u = u ∈ Point(l))
Proof
Definitions occuring in Statement : 
lattice: Lattice
, 
lattice-join: a ∨ b
, 
lattice-point: Point(l)
, 
uall: ∀[x:A]. B[x]
, 
equal: s = t ∈ T
Definitions unfolded in proof : 
uall: ∀[x:A]. B[x]
, 
member: t ∈ T
, 
lattice: Lattice
, 
and: P ∧ Q
, 
squash: ↓T
, 
prop: ℙ
, 
true: True
, 
subtype_rel: A ⊆r B
, 
uimplies: b supposing a
, 
guard: {T}
, 
iff: P 
⇐⇒ Q
, 
rev_implies: P 
⇐ Q
, 
implies: P 
⇒ Q
Lemmas referenced : 
lattice_properties, 
lattice-point_wf, 
lattice_wf, 
lattice-join_wf, 
squash_wf, 
true_wf, 
lattice-structure_wf, 
equal_wf, 
iff_weakening_equal
Rules used in proof : 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
isect_memberFormation, 
introduction, 
cut, 
extract_by_obid, 
sqequalHypSubstitution, 
isectElimination, 
thin, 
hypothesisEquality, 
hypothesis, 
setElimination, 
rename, 
productElimination, 
sqequalRule, 
isect_memberEquality, 
axiomEquality, 
because_Cache, 
applyEquality, 
lambdaEquality, 
imageElimination, 
equalityTransitivity, 
equalitySymmetry, 
universeEquality, 
natural_numberEquality, 
imageMemberEquality, 
baseClosed, 
independent_isectElimination, 
independent_functionElimination, 
hyp_replacement, 
applyLambdaEquality
Latex:
\mforall{}[l:Lattice].  \mforall{}[u:Point(l)].    (u  \mvee{}  u  =  u)
Date html generated:
2020_05_20-AM-08_25_19
Last ObjectModification:
2017_07_28-AM-09_12_46
Theory : lattices
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