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As already frequently used in the examples in this document, the
construct is used to specify the return value of a monitored
external function. In terms of ASMs, ``'' is realized as follows:
In each asm *B* that is used as monitored function, a 0-ary
dynamic function *B_result* is declared and initialized with
*no_result*, a specific element of the superuniverse. Let *R*
be the rule of *B* as defined by the user, then the internally used
rule representing the body of *B* is given by the following
conditional:

In other words, updating *B_result* with value different from
the special *no_result* element directly forces the asm to
terminate. The notation ``*t*'' in an asm *B* is then simply
an abbreviation for the update ``*B_result := t*''.

Philipp Kutter
2002-03-18