Nuprl Lemma : set_leq_iff_lt_or_eq
∀s:POSet{i}. ∀a,b:|s|.  (a ≤ b 
⇐⇒ (a <s b) ∨ (a = b ∈ |s|))
Proof
Definitions occuring in Statement : 
poset: POSet{i}
, 
set_lt: a <p b
, 
set_leq: a ≤ b
, 
set_car: |p|
, 
all: ∀x:A. B[x]
, 
iff: P 
⇐⇒ Q
, 
or: P ∨ Q
, 
equal: s = t ∈ T
Definitions unfolded in proof : 
all: ∀x:A. B[x]
, 
member: t ∈ T
, 
uall: ∀[x:A]. B[x]
, 
poset: POSet{i}
, 
qoset: QOSet
, 
dset: DSet
, 
ab_binrel: x,y:T. E[x; y]
, 
so_lambda: λ2x y.t[x; y]
, 
so_apply: x[s1;s2]
, 
prop: ℙ
, 
iff: P 
⇐⇒ Q
, 
and: P ∧ Q
, 
implies: P 
⇒ Q
, 
rev_implies: P 
⇐ Q
, 
decidable: Dec(P)
, 
or: P ∨ Q
, 
set_lt: a <p b
, 
set_blt: a <b b
, 
infix_ap: x f y
, 
cand: A c∧ B
, 
not: ¬A
, 
guard: {T}
, 
uimplies: b supposing a
, 
false: False
, 
uiff: uiff(P;Q)
Lemmas referenced : 
set_car_wf, 
poset_wf, 
poset_properties, 
qoset_wf, 
uanti_sym_wf, 
set_leq_wf, 
qoset_properties, 
dset_wf, 
upreorder_wf, 
dset_properties, 
poset_sig_wf, 
eqfun_p_wf, 
set_eq_wf, 
or_wf, 
set_lt_wf, 
equal_wf, 
decidable__dset_eq, 
assert_wf, 
band_wf, 
set_le_wf, 
bnot_wf, 
and_wf, 
not_wf, 
set_leq_antisymmetry, 
iff_transitivity, 
iff_weakening_uiff, 
assert_of_band, 
assert_of_set_leq, 
assert_of_bnot, 
set_leq_weakening_lt, 
set_leq_weakening_eq
Rules used in proof : 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
lambdaFormation, 
cut, 
lemma_by_obid, 
sqequalHypSubstitution, 
isectElimination, 
thin, 
setElimination, 
rename, 
hypothesisEquality, 
hypothesis, 
sqequalRule, 
applyEquality, 
lambdaEquality, 
setEquality, 
cumulativity, 
equalityTransitivity, 
equalitySymmetry, 
independent_pairFormation, 
dependent_functionElimination, 
unionElimination, 
inrFormation, 
inlFormation, 
because_Cache, 
independent_functionElimination, 
independent_isectElimination, 
voidElimination, 
productElimination, 
impliesFunctionality
Latex:
\mforall{}s:POSet\{i\}.  \mforall{}a,b:|s|.    (a  \mleq{}  b  \mLeftarrow{}{}\mRightarrow{}  (a  <s  b)  \mvee{}  (a  =  b))
Date html generated:
2016_05_15-PM-00_05_12
Last ObjectModification:
2015_12_26-PM-11_28_28
Theory : sets_1
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