Math: pyhasse.acm
ACMBackground
The defining equation within Hassediagram technique (HDT) and its software realization by PyHasse is:
Let be objects of an object set X, and be the indicators of a multiindicator system (mis)
The objects , are called comparable, if equation (1) holds:
: if and only if for all (1)
is the value of object , with respect to attribute . If (1) does not hold, and are »incomparable«, denoted as
The incomparability of with caused by a specific attribute pair is denoted by
(2)
The comparability of to is consequently defined by
(3)
The module ACM analyzes the incomparabilities which may appear among the objects of a userselected subset .
 Rendering the ac (antichain) matrix:
Let s be the row determined by the object pair , and t the column determined by the pair , . Then an entry of the acmatrix is defined as follows:(4)

Rowsums of acmatrix (eventually restricted to the pairs of objects resulting from a userselected subset X’), called
(5)
A large value of rss indicates that many attribute pairs are causing an incomparability of with .

Columnsums of acmatrix (eventually restricted to the pairs of objects resulting from a userselected subset , called .
(6)
with n the number of selected objects i.e.:
A large value of css indicates that the selected attribute pair (corresponding to the column t of ac) is causing incomparabilities for many object pairs taken from X'.

let w be either or , then it is of interest to find: max(w) and the corresponding list of attribute pairs (w = rs) or of object pairs (w = cs). These maximal values and associated lists inform about crucial pairs of objects and attributes, resp.