Nuprl Lemma : fun-connected-step-back

[T:Type]. ∀f:T ⟶ T. ∀x,y:T.  (x is f*(y)  is f*(f y) supposing ¬(x y ∈ T))


Proof




Definitions occuring in Statement :  fun-connected: is f*(x) uimplies: supposing a uall: [x:A]. B[x] all: x:A. B[x] not: ¬A implies:  Q apply: a function: x:A ⟶ B[x] universe: Type equal: t ∈ T
Definitions unfolded in proof :  uall: [x:A]. B[x] all: x:A. B[x] implies:  Q uimplies: supposing a member: t ∈ T not: ¬A false: False fun-connected: is f*(x) exists: x:A. B[x] or: P ∨ Q fun-path: y=f*(x) via L select: L[n] nil: [] it: so_lambda: λ2y.t[x; y] so_apply: x[s1;s2] subtract: m assert: b ifthenelse: if then else fi  btrue: tt and: P ∧ Q less_than: a < b squash: T less_than': less_than'(a;b) cons: [a b] bfalse: ff prop: append: as bs so_lambda: so_lambda3 so_apply: x[s1;s2;s3] ge: i ≥  true: True guard: {T} nat: le: A ≤ B cand: c∧ B decidable: Dec(P) iff: ⇐⇒ Q rev_implies:  Q uiff: uiff(P;Q) listp: List+ subtype_rel: A ⊆B satisfiable_int_formula: satisfiable_int_formula(fmla) int_seg: {i..j-} lelt: i ≤ j < k last: last(L) sq_type: SQType(T)
Lemmas referenced :  list-cases length_of_nil_lemma stuck-spread istype-base null_nil_lemma product_subtype_list length_of_cons_lemma reduce_hd_cons_lemma null_cons_lemma istype-void fun-connected_wf istype-universe last_lemma fun-path_wf list_ind_nil_lemma last_wf hd_wf squash_wf ge_wf length_wf list_wf listp_properties length_wf_nat decidable__lt istype-false not-lt-2 condition-implies-le minus-add minus-one-mul zero-add minus-one-mul-top add-commutes add_functionality_wrt_le add-associates add-zero le-add-cancel istype-less_than cons_wf nil_wf member-less_than append_wf length_nil non_neg_length length_cons length_append subtype_rel_list top_wf length-append full-omega-unsat intformand_wf intformnot_wf intformless_wf itermConstant_wf itermAdd_wf itermVar_wf intformle_wf istype-int int_formula_prop_and_lemma int_formula_prop_not_lemma int_formula_prop_less_lemma int_term_value_constant_lemma int_term_value_add_lemma int_term_value_var_lemma int_formula_prop_le_lemma int_formula_prop_wf hd-append-sq cons-listp int_seg_wf subtract_wf list_ind_cons_lemma decidable__le add-is-int-iff itermSubtract_wf int_term_value_subtract_lemma false_wf istype-le equal_wf true_wf select_wf select_append_front subtype_rel_self iff_weakening_equal subtype_base_sq int_subtype_base general_arith_equation1 length-singleton int_seg_properties select-nthtl0 int_seg_subtype_nat
Rules used in proof :  sqequalSubstitution sqequalTransitivity computationStep sqequalReflexivity isect_memberFormation_alt lambdaFormation_alt cut introduction sqequalRule sqequalHypSubstitution lambdaEquality_alt dependent_functionElimination thin hypothesisEquality voidElimination functionIsTypeImplies inhabitedIsType rename productElimination extract_by_obid isectElimination hypothesis unionElimination baseClosed independent_isectElimination Error :memTop,  imageElimination promote_hyp hypothesis_subsumption functionIsType equalityIstype universeIsType because_Cache instantiate universeEquality dependent_pairFormation_alt applyEquality independent_functionElimination equalityTransitivity equalitySymmetry natural_numberEquality setElimination independent_pairFormation addEquality minusEquality dependent_set_memberEquality_alt imageMemberEquality independent_pairEquality axiomEquality hyp_replacement applyLambdaEquality voidEquality approximateComputation int_eqEquality pointwiseFunctionality baseApply closedConclusion productIsType cumulativity intEquality

Latex:
\mforall{}[T:Type].  \mforall{}f:T  {}\mrightarrow{}  T.  \mforall{}x,y:T.    (x  is  f*(y)  {}\mRightarrow{}  x  is  f*(f  y)  supposing  \mneg{}(x  =  y))



Date html generated: 2020_05_20-AM-08_10_38
Last ObjectModification: 2019_12_31-PM-06_30_08

Theory : general


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