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Database
BASIC CATEGORY THEORY
Arrows (disjointified hom-sets)
df-arw
Metamath Proof Explorer
Description: Definition of the set of arrows of a category. We will use the term
"arrow" to denote a morphism tagged with its domain and codomain, as
opposed to Hom , which allows hom-sets for distinct objects to
overlap. (Contributed by Mario Carneiro , 11-Jan-2017)
Ref
Expression
Assertion
df-arw
⊢ Arrow = c ∈ Cat ⟼ ⋃ ran ⁡ Hom a ⁡ c
Detailed syntax breakdown
Step
Hyp
Ref
Expression
0
carw
class Arrow
1
vc
setvar c
2
ccat
class Cat
3
choma
class Hom a
4
1
cv
setvar c
5
4 3
cfv
class Hom a ⁡ c
6
5
crn
class ran ⁡ Hom a ⁡ c
7
6
cuni
class ⋃ ran ⁡ Hom a ⁡ c
8
1 2 7
cmpt
class c ∈ Cat ⟼ ⋃ ran ⁡ Hom a ⁡ c
9
0 8
wceq
wff Arrow = c ∈ Cat ⟼ ⋃ ran ⁡ Hom a ⁡ c