JSYML
2010
13 years 3 months ago
2010
By taking a closer look at the construction of an Ackermann function we see that between any primitive recursive degree and its Ackermann modification there is a dense chain of p...
FSTTCS
2007
Springer
13 years 10 months ago
2007
Springer
We introduce PEP, the Post Embedding Problem, a variant of PCP where one compares strings with the subword relation, and PEPreg , a further variant where solutions are constrained ...