:: deftheorem defines _zero ALTCAT_3:def 12 :
for C being non empty AltCatStr
for o1, o2 being Object of C
for M being Morphism of o1,o2 holds
( M is _zero iff for o being Object of C st o is _zero holds
for A being Morphism of o1,o
for B being Morphism of o,o2 holds M = B * A );