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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