Nuprl Lemma : interval-retraction-req
∀[u,v:ℝ]. ∀[x:{x:ℝ| x ∈ [u, v]} ].  (interval-retraction(u;v;x) = x)
Proof
Definitions occuring in Statement : 
interval-retraction: interval-retraction(u;v;r), 
rccint: [l, u], 
i-member: r ∈ I, 
req: x = y, 
real: ℝ, 
uall: ∀[x:A]. B[x], 
set: {x:A| B[x]} 
Definitions unfolded in proof : 
uall: ∀[x:A]. B[x], 
all: ∀x:A. B[x], 
member: t ∈ T, 
top: Top, 
and: P ∧ Q, 
guard: {T}, 
uimplies: b supposing a, 
interval-retraction: interval-retraction(u;v;r), 
so_lambda: λ2x.t[x], 
prop: ℙ, 
so_apply: x[s], 
subtype_rel: A ⊆r B, 
real: ℝ, 
cand: A c∧ B, 
sq_stable: SqStable(P), 
implies: P ⇒ Q, 
squash: ↓T, 
rleq: x ≤ y, 
rnonneg: rnonneg(x), 
le: A ≤ B, 
not: ¬A, 
false: False, 
uiff: uiff(P;Q), 
rev_uimplies: rev_uimplies(P;Q)
Lemmas referenced : 
member_rccint_lemma, 
rleq_transitivity, 
set_wf, 
real_wf, 
i-member_wf, 
rccint_wf, 
rleq_wf, 
less_than'_wf, 
rsub_wf, 
nat_plus_wf, 
squash_wf, 
sq_stable__rleq, 
sq_stable__and, 
rmax-req, 
rmin-req, 
req_wf, 
rmin_wf, 
rmax_wf, 
req_weakening, 
uiff_transitivity, 
req_functionality, 
rmin_functionality
Rules used in proof : 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
isect_memberFormation, 
cut, 
introduction, 
extract_by_obid, 
sqequalHypSubstitution, 
dependent_functionElimination, 
thin, 
isect_memberEquality, 
voidElimination, 
voidEquality, 
hypothesis, 
productElimination, 
isectElimination, 
because_Cache, 
hypothesisEquality, 
independent_isectElimination, 
sqequalRule, 
lambdaEquality, 
setElimination, 
rename, 
applyEquality, 
minusEquality, 
natural_numberEquality, 
independent_functionElimination, 
imageMemberEquality, 
baseClosed, 
imageElimination, 
independent_pairFormation, 
lambdaFormation, 
independent_pairEquality, 
axiomEquality, 
equalityTransitivity, 
equalitySymmetry
Latex:
\mforall{}[u,v:\mBbbR{}].  \mforall{}[x:\{x:\mBbbR{}|  x  \mmember{}  [u,  v]\}  ].    (interval-retraction(u;v;x)  =  x)
 Date html generated: 
2017_10_03-AM-10_05_39
 Last ObjectModification: 
2017_07_10-PM-05_04_39
Theory : reals
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