Nuprl Lemma : mapfilter-no-rep-fun
∀[T,U,V:Type]. ∀[eq:EqDecider(U)]. ∀[L:T List]. ∀[u:U]. ∀[f:T ⟶ U]. ∀[g:{x:{x:T| (x ∈ L)} | ↑(eq f[x] u)}  ⟶ V].
  ||mapfilter(g;λx.(eq f[x] u);L)|| ≤ 1 supposing no_repeats(U;map(f;L))
Proof
Definitions occuring in Statement : 
mapfilter: mapfilter(f;P;L), 
no_repeats: no_repeats(T;l), 
l_member: (x ∈ l), 
length: ||as||, 
map: map(f;as), 
list: T List, 
deq: EqDecider(T), 
assert: ↑b, 
uimplies: b supposing a, 
uall: ∀[x:A]. B[x], 
so_apply: x[s], 
le: A ≤ B, 
set: {x:A| B[x]} , 
apply: f a, 
lambda: λx.A[x], 
function: x:A ⟶ B[x], 
natural_number: $n, 
universe: Type
Definitions unfolded in proof : 
uall: ∀[x:A]. B[x], 
member: t ∈ T, 
deq: EqDecider(T), 
so_apply: x[s], 
subtype_rel: A ⊆r B, 
prop: ℙ, 
so_lambda: λ2x.t[x], 
and: P ∧ Q, 
uimplies: b supposing a, 
all: ∀x:A. B[x], 
implies: P ⇒ Q, 
cand: A c∧ B, 
decidable: Dec(P), 
or: P ∨ Q, 
satisfiable_int_formula: satisfiable_int_formula(fmla), 
exists: ∃x:A. B[x], 
false: False, 
not: ¬A, 
top: Top, 
le: A ≤ B, 
mapfilter: mapfilter(f;P;L), 
true: True, 
squash: ↓T, 
guard: {T}, 
iff: P ⇐⇒ Q, 
eqof: eqof(d), 
uiff: uiff(P;Q), 
less_than': less_than'(a;b), 
int_seg: {i..j-}, 
lelt: i ≤ j < k, 
less_than: a < b, 
l_before: x before y ∈ l, 
sublist: L1 ⊆ L2, 
select: L[n], 
cons: [a / b], 
subtract: n - m, 
no_repeats: no_repeats(T;l), 
ge: i ≥ j , 
nat: ℕ, 
increasing: increasing(f;k)
Lemmas referenced : 
length_wf, 
mapfilter-wf, 
subtype_rel_dep_function, 
l_member_wf, 
assert_wf, 
subtype_rel_sets, 
set_wf, 
decidable__le, 
satisfiable-full-omega-tt, 
intformand_wf, 
intformnot_wf, 
intformle_wf, 
itermConstant_wf, 
itermVar_wf, 
int_formula_prop_and_lemma, 
int_formula_prop_not_lemma, 
int_formula_prop_le_lemma, 
int_term_value_constant_lemma, 
int_term_value_var_lemma, 
int_formula_prop_wf, 
less_than'_wf, 
no_repeats_wf, 
map_wf, 
list_wf, 
deq_wf, 
length-map, 
filter_wf5, 
filter_is_sublist, 
sublist_wf, 
equal_wf, 
squash_wf, 
true_wf, 
iff_weakening_equal, 
member_filter_2, 
safe-assert-deq, 
select_wf, 
false_wf, 
decidable__lt, 
intformless_wf, 
int_formula_prop_less_lemma, 
select_member, 
lelt_wf, 
l_before_sublist, 
l_before_select, 
le_wf, 
length_of_cons_lemma, 
length_of_nil_lemma, 
int_seg_wf, 
map-length, 
non_neg_length, 
length_wf_nat, 
nat_properties, 
int_seg_properties, 
nat_wf, 
subtype_rel_list, 
top_wf, 
select-map, 
intformeq_wf, 
int_formula_prop_eq_lemma
Rules used in proof : 
cut, 
introduction, 
extract_by_obid, 
sqequalHypSubstitution, 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
isectElimination, 
thin, 
hypothesisEquality, 
because_Cache, 
lambdaEquality, 
applyEquality, 
setElimination, 
rename, 
hypothesis, 
functionExtensionality, 
cumulativity, 
sqequalRule, 
setEquality, 
productEquality, 
independent_isectElimination, 
lambdaFormation, 
productElimination, 
dependent_functionElimination, 
equalityTransitivity, 
equalitySymmetry, 
natural_numberEquality, 
unionElimination, 
dependent_pairFormation, 
int_eqEquality, 
intEquality, 
isect_memberEquality, 
voidElimination, 
voidEquality, 
independent_pairFormation, 
computeAll, 
functionEquality, 
universeEquality, 
isect_memberFormation, 
independent_pairEquality, 
axiomEquality, 
imageElimination, 
imageMemberEquality, 
baseClosed, 
independent_functionElimination, 
dependent_set_memberEquality, 
hyp_replacement, 
applyLambdaEquality
Latex:
\mforall{}[T,U,V:Type].  \mforall{}[eq:EqDecider(U)].  \mforall{}[L:T  List].  \mforall{}[u:U].  \mforall{}[f:T  {}\mrightarrow{}  U].  \mforall{}[g:\{x:\{x:T|  (x  \mmember{}  L)\}  | 
                                                                                                                                                    \muparrow{}(eq  f[x]  u)\}    {}\mrightarrow{}  V].
    ||mapfilter(g;\mlambda{}x.(eq  f[x]  u);L)||  \mleq{}  1  supposing  no\_repeats(U;map(f;L))
Date html generated:
2017_09_29-PM-06_04_32
Last ObjectModification:
2017_07_26-PM-02_53_05
Theory : decidable!equality
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