[rules-users] forall not delivering as expected

Given classes class Triangle { int a, b, c;... } class Quadrangle { int a, b, c, d;... } with appropriate getters (but no hashCode or equals) and these facts Triangle( 3, 3, 3 ) Triangle( 3, 3, 3 ) // a duplicate, intentional Quadrangle ( 3, 4, 5, 6 ); the rule rule "all equilaterals have a 'fitting' quadrangle" when forall( Triangle( $a: a, b == $a, c == $a ) Quadrangle( a == $a || b == $a || c == $a || d == $a ) ) then // ... end works as expected - it fires. But the rule rule "all equilaterals have a duplicate" when forall( $t: Triangle( $a: a, b == $a, c == $a ) Triangle( this != $t, a == $a, b == $a , c == $a ) ) then // ... end does not fire, not even when I omit this != $t. Why? Do I have a white spot in my grey cells? Please tint my taint... -W