knowledge.ipynb - Under the Minimal Consistent Determination section, a line of text is placed in a cell of type 'code' which causes an error.

Probability.ipynb - umbrella_prior not defined error. We need to define it with some value.

nlp_apps - federallist.txt not found error. The federal list papers need to be added in aima-data.
Edit: A PR for adding the Federal List papers already exists in aima-data.