Nuprl Lemma : metric-symmetry
∀[X:Type]. ∀[d:metric(X)].  ∀x,y:X.  ((d x y) = (d y x))
Proof
Definitions occuring in Statement : 
metric: metric(X), 
req: x = y, 
uall: ∀[x:A]. B[x], 
all: ∀x:A. B[x], 
apply: f a, 
universe: Type
Definitions unfolded in proof : 
uall: ∀[x:A]. B[x], 
member: t ∈ T, 
all: ∀x:A. B[x], 
metric: metric(X), 
sq_stable: SqStable(P), 
implies: P ⇒ Q, 
and: P ∧ Q, 
squash: ↓T, 
guard: {T}, 
uimplies: b supposing a, 
uiff: uiff(P;Q), 
rev_uimplies: rev_uimplies(P;Q), 
rge: x ≥ y, 
req_int_terms: t1 ≡ t2, 
false: False, 
not: ¬A, 
top: Top
Lemmas referenced : 
sq_stable__req, 
req_witness, 
metric_wf, 
istype-universe, 
radd_wf, 
int-to-real_wf, 
rleq_antisymmetry, 
rleq_functionality, 
req_weakening, 
radd_functionality, 
rleq_weakening, 
itermSubtract_wf, 
itermAdd_wf, 
itermConstant_wf, 
itermVar_wf, 
req-iff-rsub-is-0, 
rleq_functionality_wrt_implies, 
rleq_weakening_equal, 
real_polynomial_null, 
istype-int, 
real_term_value_sub_lemma, 
istype-void, 
real_term_value_add_lemma, 
real_term_value_const_lemma, 
real_term_value_var_lemma
Rules used in proof : 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
isect_memberFormation_alt, 
introduction, 
cut, 
lambdaFormation_alt, 
sqequalHypSubstitution, 
setElimination, 
thin, 
rename, 
extract_by_obid, 
isectElimination, 
applyEquality, 
hypothesisEquality, 
hypothesis, 
independent_functionElimination, 
productElimination, 
sqequalRule, 
imageMemberEquality, 
baseClosed, 
imageElimination, 
inhabitedIsType, 
universeIsType, 
lambdaEquality_alt, 
dependent_functionElimination, 
because_Cache, 
functionIsTypeImplies, 
isect_memberEquality_alt, 
isectIsTypeImplies, 
instantiate, 
universeEquality, 
natural_numberEquality, 
independent_isectElimination, 
equalityTransitivity, 
equalitySymmetry, 
approximateComputation, 
int_eqEquality, 
voidElimination
Latex:
\mforall{}[X:Type].  \mforall{}[d:metric(X)].    \mforall{}x,y:X.    ((d  x  y)  =  (d  y  x))
Date html generated:
2019_10_29-AM-10_52_35
Last ObjectModification:
2019_10_02-AM-09_34_20
Theory : reals
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