If both p and q is a path, tail(p)=tail(q) or head(p)=head(q), then (p xor q) denotes two paths. Execution of (p xor q) need to execute one of p and q.
If both p and q is a path, tail(p)=tail(q) or head(p)=head(q), then (p xor q) denotes two paths. Execution of (p xor q) need to execute one of p and q.