bijection principle (BP)

In GOVERNMENT-BINDING THEORY, a CONDITION on LOGICAL FORM which states that a VARIABLE is locally bound by one and only one A-bar position, and an A-bar position locally binds one and only one variable. This bijective correspondence excludes weak CROSSOVER violations of the type illustrated by *Who_i does his_i mother love t_i ?, which involve an A-bar position locally binding two variables (the pronoun his and the TRACE). By contrast, the principle allows Who_i t_i loves his_i mother?, where the A-bar category locally A-bar-binds the trace, which in turn locally A-binds the pronoun.