Nuprl Lemma : lattice-join-le
∀l:Lattice. ∀a,b,c:Point(l).  (a ∨ b ≤ c ⇐⇒ a ≤ c ∧ b ≤ c)
Proof
Definitions occuring in Statement : 
lattice-le: a ≤ b, 
lattice: Lattice, 
lattice-join: a ∨ b, 
lattice-point: Point(l), 
all: ∀x:A. B[x], 
iff: P ⇐⇒ Q, 
and: P ∧ Q
Definitions unfolded in proof : 
all: ∀x:A. B[x], 
member: t ∈ T, 
least-upper-bound: least-upper-bound(T;x,y.R[x; y];a;b;c), 
and: P ∧ Q, 
iff: P ⇐⇒ Q, 
implies: P ⇒ Q, 
uall: ∀[x:A]. B[x], 
lattice: Lattice, 
rev_implies: P ⇐ Q, 
prop: ℙ, 
guard: {T}, 
uimplies: b supposing a
Lemmas referenced : 
lattice-le_transitivity, 
lattice_wf, 
lattice-point_wf, 
and_wf, 
lattice-join_wf, 
lattice-le_wf, 
lattice-join-is-lub
Rules used in proof : 
cut, 
lemma_by_obid, 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
lambdaFormation, 
hypothesis, 
sqequalHypSubstitution, 
dependent_functionElimination, 
thin, 
hypothesisEquality, 
productElimination, 
independent_pairFormation, 
isectElimination, 
setElimination, 
rename, 
independent_functionElimination, 
independent_isectElimination
Latex:
\mforall{}l:Lattice.  \mforall{}a,b,c:Point(l).    (a  \mvee{}  b  \mleq{}  c  \mLeftarrow{}{}\mRightarrow{}  a  \mleq{}  c  \mwedge{}  b  \mleq{}  c)
Date html generated:
2020_05_20-AM-08_25_41
Last ObjectModification:
2016_01_19-PM-02_35_04
Theory : lattices
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