Resource is added by the execution of a goal formula .
For example, the following query adds a resource `r(1)` to the
resource table, then executes a goal `r(X)` which consumes `r(1)`
by letting .

?- r(1) -<> r(X).In the execution of the goal , all resources in

?- r(1) -<> true.

Resource formula is used to represent a rule-type resource.
The goal *G* is executed on resource consumption.
The following query displays `1`.

?- (write(X) -<> r(X)) -<> r(1).

Resource formula is used to add multiple resources.
The following query adds resources `r(1)` and `r(2)`, then
consumes both of them by letting and ,
or and .

?- (r(1), r(2)) -<> (r(X), r(Y)).

Resource formulas and mean infinite resources, that is, they can be consumed arbitrary times (including zero times). The following query succeeds by letting or .

?- (!r(1), !r(2)) -<> (r(X), r(X)).

Resource formula is used to represent a selective
resource.
For example, when `r(1)&r(2)` is added as a resource,
either `r(1)` or `r(2)` can be consumed, but not both of them.
The following query succeeds by letting or .

?- (r(1) & r(2)) -<> r(X).

Thu May 8 20:39:01 JST 1997