a situation occures more than one path exists from one table
to another table.
to reslove the loops we can use the allias ans context.
if a loop contains only one lookup table then the loop can
be resolved by detecting the alias.
if a loop is having 2 or more fact tables(multiple fact
tables) then the loop can be resolved by detecting context.

Loop can be resolved either alias/ context.

Loop is a Multiple paths between the tables selected in 
queries. Or you can say loop is a closed path structure.
  Loops can be resolved by…

 ALIASES
•Alias - Same as the namesake in SQL.
•Exact duplicate of the original table.
.A different name “tricks” the SQL query to accept that you 
are using 2 different tables.

CONTEXTS
•Rule which helps BO decide which of the 2 paths to choose 
in a loop. 
•BO prompts the user to indicate the correct perspective 
(relevant path) for the query.

When to Alias
A loop with a single lookup table should be resolved by an 
alias
A lookup table can be identified by its cardinality 
A lookup table only has the ‘one’ end of joins attached to 
it

If your universe is simple in terms of tables then go for 
alias.
If your universe is complex in terms of tables then go for 
Context.
Alias entails the propogation of the universe.
Contexts are not liked by the enduser because we are 
forcing the enduser to the database which is the against to 
the universe basic rule ie to keep the endusers away from 
the database.

loop is nothing but a continuous data flow .it is a pipe 
line.it is a close path end to end..using alias table we 
can resolve loop s

A loop is a set of joins that defines a closed path through 
a set of tables in a
schema. Loops occur when joins form multiple paths between 
lookup tables.