Transiter master theorem

From Groupprops
Revision as of 18:52, 17 September 2008 by Vipul (talk | contribs)

Statement

The version for left transiters

Suppose p is a subgroup property. Let L(p) denote the left transiter of p.

  1. If p is transitive, p is stronger than its left transiter. That is, p \le L(p)</math>.
  2. If p is identity-true, the left transiter of p is stronger than p. That is, L(p)p.
  3. if p is a t.i. subgroup property, i.e., p is both transitive and identity-true, then p=L(p).
  4. The left transiter of any property is a t.i. subgroup property, that is, it is both transitive and identity-true.

Together, (3) and (4) tell us that the left transiter operator is idempotent: L(L(p))=L(p)

The version for right transiters

Suppose p is a subgroup property. Let R(p) denote the right transiter of p.

  1. If p is transitive, p is stronger than its right transiter. That is, p \le R(p)</math>.
  2. If p is identity-true, the right transiter of p is stronger than p. That is, R(p)p.
  3. if p is a t.i. subgroup property, i.e., p is both transitive and identity-true, then p=R(p).
  4. The right transiter of any property is a t.i. subgroup property, that is, it is both transitive and identity-true.

Together, (3) and (4) tell us that the left transiter operator is idempotent: L(L(p))=L(p). Moreover, the fixed point space of this operator is the same as the fixed point space of the left transiter.

Related facts