Nuprl Lemma : product-cat_wf
∀[A,B:SmallCategory].  (A × B ∈ SmallCategory)
Proof
Definitions occuring in Statement : 
product-cat: A × B
, 
small-category: SmallCategory
, 
uall: ∀[x:A]. B[x]
, 
member: t ∈ T
Definitions unfolded in proof : 
uall: ∀[x:A]. B[x]
, 
member: t ∈ T
, 
small-category: SmallCategory
, 
product-cat: A × B
, 
pi1: fst(t)
, 
pi2: snd(t)
, 
spreadn: spread4, 
and: P ∧ Q
, 
all: ∀x:A. B[x]
, 
cand: A c∧ B
, 
squash: ↓T
, 
prop: ℙ
, 
true: True
, 
subtype_rel: A ⊆r B
, 
uimplies: b supposing a
, 
guard: {T}
, 
iff: P 
⇐⇒ Q
, 
rev_implies: P 
⇐ Q
, 
implies: P 
⇒ Q
, 
so_lambda: λ2x.t[x]
, 
so_apply: x[s]
, 
top: Top
Lemmas referenced : 
small-category_wf, 
cat-ob_wf, 
cat-arrow_wf, 
cat-id_wf, 
cat-comp_wf, 
equal_wf, 
squash_wf, 
true_wf, 
cat-comp-ident1, 
iff_weakening_equal, 
cat-comp-ident2, 
cat-comp-assoc, 
pi2_wf, 
pi1_wf_top, 
all_wf
Rules used in proof : 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
isect_memberFormation, 
dependent_set_memberEquality, 
cut, 
introduction, 
extract_by_obid, 
hypothesis, 
dependent_pairEquality, 
productEquality, 
sqequalHypSubstitution, 
isectElimination, 
thin, 
hypothesisEquality, 
functionEquality, 
cumulativity, 
universeEquality, 
applyEquality, 
functionExtensionality, 
lambdaEquality, 
productElimination, 
sqequalRule, 
because_Cache, 
independent_pairEquality, 
independent_pairFormation, 
lambdaFormation, 
imageElimination, 
equalityTransitivity, 
equalitySymmetry, 
dependent_functionElimination, 
natural_numberEquality, 
imageMemberEquality, 
baseClosed, 
independent_isectElimination, 
independent_functionElimination, 
isect_memberEquality, 
voidElimination, 
voidEquality
Latex:
\mforall{}[A,B:SmallCategory].    (A  \mtimes{}  B  \mmember{}  SmallCategory)
Date html generated:
2017_10_05-AM-00_47_54
Last ObjectModification:
2017_07_28-AM-09_19_50
Theory : small!categories
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