TY  - JOUR
AU  - J. Wallbaum
TI  - A~$\Delta^0_2$-poset with no positive presentation
JO  - Algebra i logika
PY  - 2012
SP  - 423
EP  - 428
VL  - 51
IS  - 4
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/AL_2012_51_4_a0/
LA  - ru
ID  - AL_2012_51_4_a0
ER  -