removed odd remains of structural containment checks, which stem from an older approach (see also 3ad1b289f21b, 3ae3cc4b1eac, 423af2e013b8, bad13b32c0f3, ccd6de95f4a6); de-facto this alternative never occured in practice, but it can lead to non-termination of the check;
removed odd remains of structural containment checks, which stem from an older approach (see also 3ad1b289f21b, 3ae3cc4b1eac, 423af2e013b8, bad13b32c0f3, ccd6de95f4a6);
de-facto this alternative never occured in practice, but it can lead to non-termination of the check;

MerelyAPseudonym/isabelle,MerelyAPseudonym/isabelle,MerelyAPseudonym/isabelle,MerelyAPseudonym/isabelle,MerelyAPseudonym/isabelle,MerelyAPseudonym/isabelle