Nuprl Lemma : ifthenelse_functionality_wrt_implies2

b1,b2:𝔹.  ∀[p,q1,q2:ℙ].  (b1 b2  {q1  q2}  {if b1 then else q1 fi   if b2 then else q2 fi })


Proof




Definitions occuring in Statement :  ifthenelse: if then else fi  bool: 𝔹 uall: [x:A]. B[x] prop: guard: {T} all: x:A. B[x] implies:  Q equal: t ∈ T
Definitions unfolded in proof :  guard: {T} all: x:A. B[x] uall: [x:A]. B[x] implies:  Q member: t ∈ T bool: 𝔹 unit: Unit it: btrue: tt uiff: uiff(P;Q) and: P ∧ Q uimplies: supposing a ifthenelse: if then else fi  assert: b iff: ⇐⇒ Q true: True prop: rev_implies:  Q sq_type: SQType(T) bfalse: ff exists: x:A. B[x] or: P ∨ Q bnot: ¬bb false: False
Lemmas referenced :  bool_wf eqtt_to_assert subtype_base_sq bool_subtype_base iff_imp_equal_bool btrue_wf assert_wf true_wf eqff_to_assert equal_wf bool_cases_sqequal assert_of_bnot ifthenelse_wf
Rules used in proof :  sqequalSubstitution sqequalRule sqequalReflexivity sqequalTransitivity computationStep lambdaFormation isect_memberFormation cut hypothesisEquality thin introduction extract_by_obid hypothesis sqequalHypSubstitution unionElimination equalityElimination isectElimination productElimination independent_isectElimination instantiate cumulativity independent_pairFormation natural_numberEquality because_Cache dependent_functionElimination independent_functionElimination equalityTransitivity equalitySymmetry dependent_pairFormation promote_hyp voidElimination universeEquality functionEquality

Latex:
\mforall{}b1,b2:\mBbbB{}.
    \mforall{}[p,q1,q2:\mBbbP{}].    (b1  =  b2  {}\mRightarrow{}  \{q1  {}\mRightarrow{}  q2\}  {}\mRightarrow{}  \{if  b1  then  p  else  q1  fi    {}\mRightarrow{}  if  b2  then  p  else  q2  fi  \})



Date html generated: 2017_04_14-AM-07_30_03
Last ObjectModification: 2017_02_27-PM-02_58_35

Theory : bool_1


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