Nuprl Lemma : square-between
∀a:{a:ℚ| 0 ≤ a} . ∀b:{b:ℚ| a < b} .  (∃r:ℚ [(a < r * r < b ∧ 0 < r)])
Proof
Definitions occuring in Statement : 
q-between: a < b < c, 
qle: r ≤ s, 
qless: r < s, 
qmul: r * s, 
rationals: ℚ, 
all: ∀x:A. B[x], 
sq_exists: ∃x:A [B[x]], 
and: P ∧ Q, 
set: {x:A| B[x]} , 
natural_number: $n
Definitions unfolded in proof : 
all: ∀x:A. B[x], 
uall: ∀[x:A]. B[x], 
member: t ∈ T, 
implies: P ⇒ Q, 
prop: ℙ, 
so_lambda: λ2x.t[x], 
and: P ∧ Q, 
subtype_rel: A ⊆r B, 
so_apply: x[s], 
uimplies: b supposing a, 
nat_plus: ℕ+, 
sq_type: SQType(T), 
guard: {T}, 
sq_stable: SqStable(P), 
squash: ↓T, 
qle: r ≤ s, 
grp_leq: a ≤ b, 
qadd_grp: <ℚ+>, 
grp_le: ≤b, 
pi2: snd(t), 
pi1: fst(t), 
infix_ap: x f y, 
q_le: q_le(r;s), 
callbyvalueall: callbyvalueall, 
evalall: evalall(t), 
has-value: (a)↓, 
has-valueall: has-valueall(a), 
qeq: qeq(r;s), 
qsub: r - s, 
qpositive: qpositive(r), 
qmul: r * s, 
ifthenelse: if b then t else f fi , 
btrue: tt, 
qadd: r + s, 
bfalse: ff, 
or: P ∨ Q, 
uiff: uiff(P;Q), 
band: p ∧b q, 
decidable: Dec(P), 
not: ¬A, 
satisfiable_int_formula: satisfiable_int_formula(fmla), 
exists: ∃x:A. B[x], 
false: False, 
top: Top, 
iff: P ⇐⇒ Q, 
rev_implies: P ⇐ Q, 
mk-rational: mk-rational(a;b), 
q_less: q_less(r;s), 
cand: A c∧ B, 
nat: ℕ, 
sq_exists: ∃x:A [B[x]], 
let: let, 
ge: i ≥ j , 
int_nzero: ℤ-o, 
nequal: a ≠ b ∈ T , 
true: True, 
less_than: a < b, 
le: A ≤ B, 
subtract: n - m, 
q-between: a < b < c, 
rev_uimplies: rev_uimplies(P;Q)
Lemmas referenced : 
equals-qrep, 
qrep-denom, 
sq_exists_wf, 
rationals_wf, 
q-between_wf, 
qrep_wf, 
qmul_wf, 
qless_wf, 
qle_wf, 
int-subtype-rationals, 
subtype_base_sq, 
nat_plus_wf, 
product_subtype_base, 
int_subtype_base, 
set_subtype_base, 
less_than_wf, 
sq_stable_from_decidable, 
decidable__qle, 
valueall-type-has-valueall, 
product-valueall-type, 
int-valueall-type, 
set-valueall-type, 
evalall-reduce, 
assert_wf, 
bor_wf, 
lt_int_wf, 
bool_cases, 
bool_wf, 
bool_subtype_base, 
eqtt_to_assert, 
band_wf, 
btrue_wf, 
assert_of_lt_int, 
bfalse_wf, 
eq_int_wf, 
equal-wf-base, 
istype-assert, 
istype-less_than, 
nat_plus_properties, 
decidable__le, 
full-omega-unsat, 
intformand_wf, 
intformnot_wf, 
intformle_wf, 
itermConstant_wf, 
itermVar_wf, 
intformor_wf, 
intformless_wf, 
itermAdd_wf, 
itermMultiply_wf, 
istype-int, 
int_formula_prop_and_lemma, 
istype-void, 
int_formula_prop_not_lemma, 
int_formula_prop_le_lemma, 
int_term_value_constant_lemma, 
int_term_value_var_lemma, 
int_formula_prop_or_lemma, 
int_formula_prop_less_lemma, 
int_term_value_add_lemma, 
int_term_value_mul_lemma, 
int_formula_prop_wf, 
intformeq_wf, 
int_formula_prop_eq_lemma, 
iff_transitivity, 
iff_weakening_uiff, 
assert_of_bor, 
assert_of_band, 
assert_of_eq_int, 
decidable__qless, 
assert-q_less-eq, 
mk-rational_wf, 
nat_plus_inc_int_nzero, 
iff_weakening_equal, 
mul_bounds_1b, 
decidable__lt, 
bnot_wf, 
not_wf, 
eqff_to_assert, 
assert_of_bnot, 
mul_bounds_1a, 
istype-le, 
nat_plus_subtype_nat, 
isqrt_wf, 
nat_properties, 
add_nat_plus, 
add-is-int-iff, 
false_wf, 
qdiv_wf, 
multiply_nat_wf, 
int_nzero-rational, 
int_entire_a, 
nequal_wf, 
mul_nat_plus, 
isqrt-property, 
equal_wf, 
squash_wf, 
true_wf, 
istype-universe, 
subtype_rel_self, 
add_functionality_wrt_eq, 
istype-nat, 
itermMinus_wf, 
int_term_value_minus_lemma, 
mul_preserves_lt, 
nat_wf, 
le_wf, 
decidable__equal_int, 
mul-distributes, 
mul-distributes-right, 
add-associates, 
mul-swap, 
mul-commutes, 
mul-associates, 
one-mul, 
two-mul, 
add-commutes, 
add-swap, 
subtract_wf, 
itermSubtract_wf, 
int_term_value_subtract_lemma, 
mul_preserves_le, 
mk-rational-qdiv, 
qmul_preserves_qless, 
qless-int, 
subtype_rel_set, 
qmul-mul, 
qmul_assoc_qrng, 
qmul_comm_qrng, 
qmul_ac_1_qrng, 
qmul-qdiv-cancel3, 
qless_transitivity_2_qorder, 
qle_weakening_eq_qorder, 
qless_irreflexivity, 
qmul_zero_qrng, 
qmul-qdiv-cancel
Rules used in proof : 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
lambdaFormation_alt, 
cut, 
introduction, 
extract_by_obid, 
sqequalHypSubstitution, 
isectElimination, 
thin, 
setElimination, 
rename, 
hypothesisEquality, 
hypothesis, 
equalitySymmetry, 
because_Cache, 
equalityTransitivity, 
inhabitedIsType, 
productElimination, 
equalityIstype, 
dependent_functionElimination, 
independent_functionElimination, 
hyp_replacement, 
applyLambdaEquality, 
sqequalRule, 
lambdaEquality_alt, 
productEquality, 
natural_numberEquality, 
applyEquality, 
setIsType, 
universeIsType, 
instantiate, 
cumulativity, 
intEquality, 
independent_isectElimination, 
imageMemberEquality, 
baseClosed, 
imageElimination, 
callbyvalueReduce, 
sqleReflexivity, 
isintReduceTrue, 
independent_pairEquality, 
addEquality, 
multiplyEquality, 
unionElimination, 
unionEquality, 
baseApply, 
closedConclusion, 
isect_memberEquality_alt, 
productIsType, 
unionIsType, 
sqequalBase, 
approximateComputation, 
dependent_pairFormation_alt, 
int_eqEquality, 
voidElimination, 
independent_pairFormation, 
inlFormation_alt, 
promote_hyp, 
inrFormation_alt, 
functionIsType, 
dependent_set_memberEquality_alt, 
dependent_set_memberFormation_alt, 
pointwiseFunctionality, 
universeEquality, 
minusEquality
Latex:
\mforall{}a:\{a:\mBbbQ{}|  0  \mleq{}  a\}  .  \mforall{}b:\{b:\mBbbQ{}|  a  <  b\}  .    (\mexists{}r:\mBbbQ{}  [(a  <  r  *  r  <  b  \mwedge{}  0  <  r)])
Date html generated:
2019_10_16-PM-00_38_33
Last ObjectModification:
2019_06_26-PM-04_14_56
Theory : rationals
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