Nuprl Lemma : IVT-locally-non-constant-open
∀a:ℝ. ∀b:{b:ℝ| a < b} . ∀f:[a, b] ⟶ℝ.
  (∀a',b':ℝ.  (((a < a') ∧ (a' < b') ∧ (b' < b)) 
⇒ (∀c:ℝ. locally-non-constant(f;a';b';c))))
  
⇒ (∀c:ℝ. ((f(a) < c) 
⇒ (c < f(b)) 
⇒ (∃x:ℝ. ((x ∈ (a, b)) ∧ (f(x) = c))))) 
  supposing ∀x,y:{x:ℝ| x ∈ [a, b]} .  ((x = y) 
⇒ (f[x] = f[y]))
Proof
Definitions occuring in Statement : 
locally-non-constant: locally-non-constant(f;a;b;c)
, 
r-ap: f(x)
, 
rfun: I ⟶ℝ
, 
rooint: (l, u)
, 
rccint: [l, u]
, 
i-member: r ∈ I
, 
rless: x < y
, 
req: x = y
, 
real: ℝ
, 
uimplies: b supposing a
, 
so_apply: x[s]
, 
all: ∀x:A. B[x]
, 
exists: ∃x:A. B[x]
, 
implies: P 
⇒ Q
, 
and: P ∧ Q
, 
set: {x:A| B[x]} 
Definitions unfolded in proof : 
all: ∀x:A. B[x]
, 
subinterval: I ⊆ J 
, 
member: t ∈ T
, 
top: Top
, 
implies: P 
⇒ Q
, 
and: P ∧ Q
, 
cand: A c∧ B
, 
uall: ∀[x:A]. B[x]
, 
guard: {T}
, 
uimplies: b supposing a
, 
prop: ℙ
, 
sq_stable: SqStable(P)
, 
squash: ↓T
, 
so_apply: x[s]
, 
rfun: I ⟶ℝ
, 
so_lambda: λ2x.t[x]
, 
i-member: r ∈ I
, 
rccint: [l, u]
, 
subtype_rel: A ⊆r B
, 
continuous: f[x] continuous for x ∈ I
, 
i-approx: i-approx(I;n)
, 
nat_plus: ℕ+
, 
rless: x < y
, 
sq_exists: ∃x:A [B[x]]
, 
decidable: Dec(P)
, 
or: P ∨ Q
, 
not: ¬A
, 
satisfiable_int_formula: satisfiable_int_formula(fmla)
, 
exists: ∃x:A. B[x]
, 
false: False
, 
iff: P 
⇐⇒ Q
, 
rneq: x ≠ y
, 
rev_implies: P 
⇐ Q
, 
rleq: x ≤ y
, 
rnonneg: rnonneg(x)
, 
le: A ≤ B
, 
uiff: uiff(P;Q)
, 
req_int_terms: t1 ≡ t2
, 
rev_uimplies: rev_uimplies(P;Q)
, 
less_than': less_than'(a;b)
, 
rge: x ≥ y
, 
r-ap: f(x)
, 
rdiv: (x/y)
Lemmas referenced : 
member_rooint_lemma, 
istype-void, 
member_rccint_lemma, 
rleq_weakening_rless, 
rless_wf, 
sq_stable__rless, 
req_witness, 
function-is-continuous, 
r-ap_wf, 
rccint_wf, 
rleq_weakening_equal, 
locally-non-constant_wf, 
rfun_subtype_3, 
i-member_wf, 
req_wf, 
rfun_wf, 
real_wf, 
nat_plus_properties, 
decidable__lt, 
full-omega-unsat, 
intformnot_wf, 
intformless_wf, 
itermConstant_wf, 
istype-int, 
int_formula_prop_not_lemma, 
int_formula_prop_less_lemma, 
int_term_value_constant_lemma, 
int_formula_prop_wf, 
istype-less_than, 
rccint-icompact, 
icompact_wf, 
small-reciprocal-real, 
rless-implies-rless, 
int-to-real_wf, 
rsub_wf, 
sq_stable__and, 
all_wf, 
rleq_wf, 
rabs_wf, 
rdiv_wf, 
rless-int, 
intformand_wf, 
itermVar_wf, 
int_formula_prop_and_lemma, 
int_term_value_var_lemma, 
sq_stable__all, 
sq_stable__rleq, 
le_witness_for_triv, 
itermSubtract_wf, 
req-iff-rsub-is-0, 
real_polynomial_null, 
real_term_value_sub_lemma, 
real_term_value_var_lemma, 
real_term_value_const_lemma, 
ravg-between, 
rmin_strict_ub, 
radd_wf, 
ravg_wf, 
trivial-rless-radd, 
rmin_strict_lb, 
rmin_wf, 
rabs-difference-bound-rleq, 
radd-preserves-rleq, 
rminus_wf, 
itermAdd_wf, 
itermMinus_wf, 
rmin_ub, 
rleq_functionality, 
real_term_value_add_lemma, 
rmin_lb, 
real_term_value_minus_lemma, 
rmul_wf, 
itermMultiply_wf, 
rmul-nonneg-case1, 
rleq-int, 
istype-false, 
real_term_value_mul_lemma, 
rleq_functionality_wrt_implies, 
radd_functionality_wrt_rleq, 
req_weakening, 
rinv_wf2, 
req_transitivity, 
radd_functionality, 
rinv-as-rdiv, 
radd-preserves-rless, 
rless_functionality_wrt_implies, 
rless_functionality, 
rmax_strict_lb, 
trivial-rsub-rless, 
rmax_strict_ub, 
rmax_wf, 
rless_transitivity2, 
rleq-rmax, 
rmax_lb, 
trivial-rleq-radd, 
nat_plus_wf, 
IVT-locally-non-constant, 
rless_transitivity1, 
sq_stable__req, 
sq_stable__i-member, 
rleq_transitivity, 
rleq_weakening, 
req_inversion, 
continuous-implies-functional
Rules used in proof : 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
lambdaFormation_alt, 
cut, 
sqequalRule, 
introduction, 
extract_by_obid, 
sqequalHypSubstitution, 
dependent_functionElimination, 
thin, 
isect_memberEquality_alt, 
voidElimination, 
hypothesis, 
productElimination, 
isectElimination, 
hypothesisEquality, 
independent_isectElimination, 
independent_pairFormation, 
setElimination, 
rename, 
because_Cache, 
productIsType, 
universeIsType, 
independent_functionElimination, 
imageMemberEquality, 
baseClosed, 
imageElimination, 
isect_memberFormation_alt, 
lambdaEquality_alt, 
applyEquality, 
functionIsTypeImplies, 
inhabitedIsType, 
promote_hyp, 
functionIsType, 
setIsType, 
dependent_set_memberEquality_alt, 
natural_numberEquality, 
unionElimination, 
approximateComputation, 
dependent_pairFormation_alt, 
functionEquality, 
productEquality, 
closedConclusion, 
inrFormation_alt, 
int_eqEquality, 
equalityTransitivity, 
equalitySymmetry, 
inlFormation_alt
Latex:
\mforall{}a:\mBbbR{}.  \mforall{}b:\{b:\mBbbR{}|  a  <  b\}  .  \mforall{}f:[a,  b]  {}\mrightarrow{}\mBbbR{}.
    (\mforall{}a',b':\mBbbR{}.    (((a  <  a')  \mwedge{}  (a'  <  b')  \mwedge{}  (b'  <  b))  {}\mRightarrow{}  (\mforall{}c:\mBbbR{}.  locally-non-constant(f;a';b';c))))
    {}\mRightarrow{}  (\mforall{}c:\mBbbR{}.  ((f(a)  <  c)  {}\mRightarrow{}  (c  <  f(b))  {}\mRightarrow{}  (\mexists{}x:\mBbbR{}.  ((x  \mmember{}  (a,  b))  \mwedge{}  (f(x)  =  c))))) 
    supposing  \mforall{}x,y:\{x:\mBbbR{}|  x  \mmember{}  [a,  b]\}  .    ((x  =  y)  {}\mRightarrow{}  (f[x]  =  f[y]))
Date html generated:
2019_10_30-AM-09_09_15
Last ObjectModification:
2019_04_02-AM-11_58_05
Theory : reals
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