Nuprl Lemma : single-valued-bag-hd
∀[T:Type]. ∀[b:bag(T)].  (hd(b) ∈ T) supposing (0 < #(b) and single-valued-bag(b;T))
Proof
Definitions occuring in Statement : 
single-valued-bag: single-valued-bag(b;T)
, 
bag-size: #(bs)
, 
bag: bag(T)
, 
hd: hd(l)
, 
less_than: a < b
, 
uimplies: b supposing a
, 
uall: ∀[x:A]. B[x]
, 
member: t ∈ T
, 
natural_number: $n
, 
universe: Type
Definitions unfolded in proof : 
uall: ∀[x:A]. B[x]
, 
member: t ∈ T
, 
uimplies: b supposing a
, 
bag: bag(T)
, 
all: ∀x:A. B[x]
, 
prop: ℙ
, 
quotient: x,y:A//B[x; y]
, 
and: P ∧ Q
, 
bag-size: #(bs)
, 
listp: A List+
, 
squash: ↓T
, 
true: True
, 
subtype_rel: A ⊆r B
, 
nat: ℕ
, 
permutation: permutation(T;L1;L2)
, 
exists: ∃x:A. B[x]
, 
top: Top
, 
le: A ≤ B
, 
less_than': less_than'(a;b)
, 
false: False
, 
not: ¬A
, 
implies: P 
⇒ Q
, 
int_seg: {i..j-}
, 
lelt: i ≤ j < k
, 
guard: {T}
, 
iff: P 
⇐⇒ Q
, 
rev_implies: P 
⇐ Q
, 
single-valued-bag: single-valued-bag(b;T)
, 
ge: i ≥ j 
, 
decidable: Dec(P)
, 
or: P ∨ Q
, 
satisfiable_int_formula: satisfiable_int_formula(fmla)
, 
so_lambda: λ2x.t[x]
, 
so_apply: x[s]
Lemmas referenced : 
list_wf, 
permutation_wf, 
permutation_weakening, 
hd_wf, 
listp_properties, 
less_than_wf, 
length_wf, 
equal-wf-base, 
member_wf, 
squash_wf, 
true_wf, 
bag-size_wf, 
nat_wf, 
single-valued-bag_wf, 
bag_wf, 
permutation-length, 
length_wf_nat, 
equal_wf, 
select0, 
select_wf, 
false_wf, 
permute_list_select, 
lelt_wf, 
subtype_rel_self, 
iff_weakening_equal, 
int_seg_wf, 
non_neg_length, 
decidable__le, 
nat_properties, 
int_seg_properties, 
full-omega-unsat, 
intformand_wf, 
intformle_wf, 
itermConstant_wf, 
itermVar_wf, 
intformnot_wf, 
int_formula_prop_and_lemma, 
int_formula_prop_le_lemma, 
int_term_value_constant_lemma, 
int_term_value_var_lemma, 
int_formula_prop_not_lemma, 
int_formula_prop_wf, 
decidable__lt, 
intformless_wf, 
int_formula_prop_less_lemma, 
bag-member-select, 
subtype_rel_sets, 
less_than_transitivity1, 
le_weakening
Rules used in proof : 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
isect_memberFormation, 
introduction, 
cut, 
sqequalHypSubstitution, 
extract_by_obid, 
isectElimination, 
thin, 
hypothesisEquality, 
hypothesis, 
promote_hyp, 
lambdaFormation, 
equalityTransitivity, 
equalitySymmetry, 
because_Cache, 
dependent_functionElimination, 
independent_isectElimination, 
pointwiseFunctionality, 
sqequalRule, 
pertypeElimination, 
productElimination, 
cumulativity, 
dependent_set_memberEquality, 
natural_numberEquality, 
productEquality, 
applyEquality, 
lambdaEquality, 
imageElimination, 
imageMemberEquality, 
baseClosed, 
axiomEquality, 
setElimination, 
rename, 
isect_memberEquality, 
universeEquality, 
voidElimination, 
voidEquality, 
independent_pairFormation, 
instantiate, 
independent_functionElimination, 
functionExtensionality, 
unionElimination, 
applyLambdaEquality, 
approximateComputation, 
dependent_pairFormation, 
int_eqEquality, 
intEquality, 
hyp_replacement, 
setEquality
Latex:
\mforall{}[T:Type].  \mforall{}[b:bag(T)].    (hd(b)  \mmember{}  T)  supposing  (0  <  \#(b)  and  single-valued-bag(b;T))
Date html generated:
2018_05_21-PM-06_24_57
Last ObjectModification:
2018_05_19-PM-05_15_26
Theory : bags
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