© 2001 by Oxford University Press
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Ackermann's Implication for Typefree Logic
1 Technische Universitaet Berlin, FB Informatik, FR 6-10, Franklinstr. 28, D-10587 Berlin, Germany. krob{at}cs.tu-berlin.de
We study the positive fragment of a system of partial logic which has been
developed by Ackermann in the course of his typefree foundation of mathematics.
One of the prominent features of this system is its implication, which has
been supplied with a deductive interpretation according to which
A
B expresses that B is derivable
from A. The first section provides Ackermann's original
Hilbert-style formulation of the positive part of his logic and a new
formulation using natural deduction. Elaborating Ackermann's idea concerning
the interpretation of
, another new characterization of his positive
logic is given in terms of a sequence of consecutive deductive systems. The
last section contains a brief account of the algebraic semantics of Ackermann's
system, which has not been considered in the literature up to now.
Keywords: Typefree logics; implicative logic; substructural logics
Accepted April 2000.