any one (_)

The any one operator _ is a path operator that is used to specify any one possible node in a path.

Syntax

The syntax of _ is as follows:

   node_i/_ -> _/node_j

Any one operator _ must be used in a path.

Scope

The any one path operator _ can only be used in goal section.

Semantics

A path contains one or more any one operators (_) is considered by Cyclone as long as a node in a graph can form a valid path. Given a path condition: S_x->_->S_y, the node picked between S_x and S_y depends on the solver and the connections between S_x and S_y(see the following graph). Any one operator means that it could be any one of these nodes: S₀,...,S_i,S_i+1,S_i+2,...S_n.

Hence, the above path condition is equivalent to the following compound path condition:

S_x->S₀->S_y || S_x->S_i->S_y || ... ||S_x->S_n->S_y

Example

 _->S1->_

A path has length of 2, and must have node S1 in the middle.

 S1->_->_->S1

A path has length of 3, and must begin and end with node S1.

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