when a schema contains a loop u should create alias 
table..alias concept not only for loops.we can also use 
in fantraps.
coming to context :when u run two sql statements as a 
singlestatemnt we will go for context detection process.

in traps we can choose contexts.
traps are two types chasam trap and  fan trap.

these traps are situvation oriented
relation betwen muliple tables like this:
--------------------------------------0-

chasam trap :1:M:1
fan trap    :1:M 1:M

really if u want o see the context how to look
tools->automatic detection----.detect contexts in BO XIr2