Removed outcommented legacy content.
Added a label informing us that wBisim_incruent is also an example for the strictness of the inclusion of observational congruence and weak bisimilarity.
Added an example that shows that strong bisimilarity is not contained in observational congruence.
Extended tr_notIn_ttr by the weak conterparts of trace equivalence.
Switched off page numbers.
Added a remark stressing that relations are defined for expressions rather than LTS.
Added the sBiSim_notIn_congruence example and fiddled around with the spacing to make it all fit on a single page.