A Framework of Directionality for Proving Termination of Logic Programs. - François Bronsard; T. K. Lakshman; Uday S. Reddy (JICSLP, 1992)

Soft Typing with Conditional Types. - Alexander Aiken; Edward L. Wimmers; T. K. Lakshman (POPL, 1994)

Directional Type Checking of Logic Programs - Alexander Aiken; T. K. Lakshman (SAS, 1994)