Nuprl Lemma : i-member-convex'

I:Interval. ∀a,b:ℝ.
  ((a ∈ I)  (b ∈ I)  (∀z:{z:ℝr0 < z} . ∀x,y:{z:ℝr0 ≤ z} .  (((x y) z)  (((x a) (y b)/z) ∈ I))))


Proof




Definitions occuring in Statement :  i-member: r ∈ I interval: Interval rdiv: (x/y) rleq: x ≤ y rless: x < y req: y rmul: b radd: b int-to-real: r(n) real: all: x:A. B[x] implies:  Q set: {x:A| B[x]}  natural_number: $n
Definitions unfolded in proof :  all: x:A. B[x] implies:  Q member: t ∈ T uall: [x:A]. B[x] uimplies: supposing a rneq: x ≠ y guard: {T} or: P ∨ Q sq_stable: SqStable(P) squash: T prop: uiff: uiff(P;Q) and: P ∧ Q rev_uimplies: rev_uimplies(P;Q) rdiv: (x/y) req_int_terms: t1 ≡ t2 false: False not: ¬A top: Top iff: ⇐⇒ Q
Lemmas referenced :  i-member-convex rdiv_wf sq_stable__rless int-to-real_wf rless_wf req_wf radd_wf rleq_wf i-member_wf real_wf interval_wf rmul_preserves_rleq rmul_wf itermSubtract_wf itermMultiply_wf itermConstant_wf itermVar_wf rinv_wf2 sq_stable__rleq rleq_functionality req_transitivity rmul_functionality req_weakening rmul-rinv req-iff-rsub-is-0 real_polynomial_null istype-int real_term_value_sub_lemma istype-void real_term_value_mul_lemma real_term_value_const_lemma real_term_value_var_lemma trivial-rleq-radd req_inversion rmul_preserves_req rsub_wf rminus_wf itermAdd_wf itermMinus_wf req_functionality radd_functionality rminus_functionality real_term_value_add_lemma real_term_value_minus_lemma req-implies-req i-member_functionality
Rules used in proof :  sqequalSubstitution sqequalTransitivity computationStep sqequalReflexivity lambdaFormation_alt cut introduction extract_by_obid sqequalHypSubstitution dependent_functionElimination thin hypothesisEquality independent_functionElimination hypothesis isectElimination setElimination rename because_Cache independent_isectElimination sqequalRule inrFormation_alt natural_numberEquality imageMemberEquality baseClosed imageElimination universeIsType inhabitedIsType setIsType productElimination approximateComputation lambdaEquality_alt int_eqEquality isect_memberEquality_alt voidElimination equalityTransitivity equalitySymmetry closedConclusion

Latex:
\mforall{}I:Interval.  \mforall{}a,b:\mBbbR{}.
    ((a  \mmember{}  I)
    {}\mRightarrow{}  (b  \mmember{}  I)
    {}\mRightarrow{}  (\mforall{}z:\{z:\mBbbR{}|  r0  <  z\}  .  \mforall{}x,y:\{z:\mBbbR{}|  r0  \mleq{}  z\}  .    (((x  +  y)  =  z)  {}\mRightarrow{}  (((x  *  a)  +  (y  *  b)/z)  \mmember{}  I))))



Date html generated: 2019_10_29-AM-10_46_52
Last ObjectModification: 2019_01_08-PM-06_10_39

Theory : reals


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