Nuprl Lemma : combine-rless
∀a,b,c,d:ℝ.  ((a < b) ⇒ (c < d) ⇒ (((b * c) + (a * d)) < ((b * d) + (a * c))))
Proof
Definitions occuring in Statement : 
rless: x < y, 
rmul: a * b, 
radd: a + b, 
real: ℝ, 
all: ∀x:A. B[x], 
implies: P ⇒ Q
Definitions unfolded in proof : 
all: ∀x:A. B[x], 
implies: P ⇒ Q, 
member: t ∈ T, 
uall: ∀[x:A]. B[x], 
iff: P ⇐⇒ Q, 
and: P ∧ Q, 
rev_implies: P ⇐ Q, 
or: P ∨ Q, 
cand: A c∧ B, 
uimplies: b supposing a, 
prop: ℙ, 
uiff: uiff(P;Q), 
req_int_terms: t1 ≡ t2, 
false: False, 
not: ¬A, 
top: Top
Lemmas referenced : 
rmul-is-positive, 
rsub_wf, 
rless-implies-rless, 
int-to-real_wf, 
rless_wf, 
radd_wf, 
rmul_wf, 
real_wf, 
itermSubtract_wf, 
itermVar_wf, 
itermConstant_wf, 
req-iff-rsub-is-0, 
itermMultiply_wf, 
itermAdd_wf, 
real_polynomial_null, 
istype-int, 
real_term_value_sub_lemma, 
istype-void, 
real_term_value_var_lemma, 
real_term_value_const_lemma, 
real_term_value_mul_lemma, 
real_term_value_add_lemma
Rules used in proof : 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
lambdaFormation_alt, 
cut, 
introduction, 
extract_by_obid, 
sqequalHypSubstitution, 
dependent_functionElimination, 
thin, 
isectElimination, 
hypothesisEquality, 
hypothesis, 
productElimination, 
independent_functionElimination, 
inlFormation_alt, 
natural_numberEquality, 
because_Cache, 
independent_isectElimination, 
independent_pairFormation, 
sqequalRule, 
productIsType, 
universeIsType, 
inhabitedIsType, 
approximateComputation, 
lambdaEquality_alt, 
int_eqEquality, 
isect_memberEquality_alt, 
voidElimination
Latex:
\mforall{}a,b,c,d:\mBbbR{}.    ((a  <  b)  {}\mRightarrow{}  (c  <  d)  {}\mRightarrow{}  (((b  *  c)  +  (a  *  d))  <  ((b  *  d)  +  (a  *  c))))
 Date html generated: 
2019_10_29-AM-10_05_29
 Last ObjectModification: 
2019_04_09-AM-10_58_54
Theory : reals
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