Nuprl Lemma : bag-member-implies-hd-append
∀[T:Type]. ∀[x:T]. ∀[b:bag(T)].  ↓∃c:bag(T). (b = ({x} + c) ∈ bag(T)) supposing x ↓∈ b
Proof
Definitions occuring in Statement : 
bag-member: x ↓∈ bs
, 
bag-append: as + bs
, 
single-bag: {x}
, 
bag: bag(T)
, 
uimplies: b supposing a
, 
uall: ∀[x:A]. B[x]
, 
exists: ∃x:A. B[x]
, 
squash: ↓T
, 
universe: Type
, 
equal: s = t ∈ T
Definitions unfolded in proof : 
uall: ∀[x:A]. B[x]
, 
member: t ∈ T
, 
uimplies: b supposing a
, 
squash: ↓T
, 
exists: ∃x:A. B[x]
, 
prop: ℙ
, 
bag-member: x ↓∈ bs
, 
and: P ∧ Q
, 
l_member: (x ∈ l)
, 
cand: A c∧ B
, 
nat: ℕ
, 
subtype_rel: A ⊆r B
, 
single-bag: {x}
, 
bag-append: as + bs
, 
append: as @ bs
, 
all: ∀x:A. B[x]
, 
so_lambda: so_lambda(x,y,z.t[x; y; z])
, 
top: Top
, 
so_apply: x[s1;s2;s3]
, 
bag: bag(T)
, 
so_lambda: λ2x y.t[x; y]
, 
so_apply: x[s1;s2]
, 
ge: i ≥ j 
, 
decidable: Dec(P)
, 
or: P ∨ Q
, 
satisfiable_int_formula: satisfiable_int_formula(fmla)
, 
false: False
, 
implies: P 
⇒ Q
, 
not: ¬A
, 
so_lambda: λ2x.t[x]
, 
so_apply: x[s]
, 
iff: P 
⇐⇒ Q
, 
rev_implies: P 
⇐ Q
, 
int_seg: {i..j-}
, 
lelt: i ≤ j < k
, 
le: A ≤ B
, 
int_iseg: {i...j}
Lemmas referenced : 
bag_to_squash_list, 
bag-member_wf, 
reject_wf, 
list-subtype-bag, 
list_ind_cons_lemma, 
list_ind_nil_lemma, 
quotient-member-eq, 
list_wf, 
permutation_wf, 
permutation-equiv, 
cons_wf, 
select_wf, 
nat_properties, 
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, 
equal_wf, 
bag_wf, 
bag-append_wf, 
single-bag_wf, 
squash_wf, 
exists_wf, 
permutation_inversion, 
permutation-cons, 
firstn_nth_tl_decomp, 
lelt_wf, 
length_wf, 
firstn_wf, 
nth_tl_wf, 
append_wf, 
permutation_weakening, 
reject_eq_firstn_nth_tl, 
length-append, 
length_firstn, 
length_of_cons_lemma, 
intformless_wf, 
int_formula_prop_less_lemma, 
le_wf
Rules used in proof : 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
isect_memberFormation, 
introduction, 
cut, 
extract_by_obid, 
sqequalHypSubstitution, 
isectElimination, 
thin, 
because_Cache, 
hypothesisEquality, 
imageElimination, 
productElimination, 
promote_hyp, 
hypothesis, 
equalitySymmetry, 
hyp_replacement, 
applyLambdaEquality, 
cumulativity, 
rename, 
dependent_pairFormation, 
setElimination, 
applyEquality, 
independent_isectElimination, 
lambdaEquality, 
sqequalRule, 
dependent_functionElimination, 
isect_memberEquality, 
voidElimination, 
voidEquality, 
natural_numberEquality, 
unionElimination, 
int_eqEquality, 
intEquality, 
independent_pairFormation, 
computeAll, 
independent_functionElimination, 
imageMemberEquality, 
baseClosed, 
equalityTransitivity, 
universeEquality, 
dependent_set_memberEquality, 
addEquality, 
productEquality
Latex:
\mforall{}[T:Type].  \mforall{}[x:T].  \mforall{}[b:bag(T)].    \mdownarrow{}\mexists{}c:bag(T).  (b  =  (\{x\}  +  c))  supposing  x  \mdownarrow{}\mmember{}  b
Date html generated:
2017_10_01-AM-08_55_47
Last ObjectModification:
2017_07_26-PM-04_37_53
Theory : bags
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