λδ is developed in the context of the
<link to="http://helm.cs.unibo.it/">Hypertextual Electronic Library of Mathematics</link>
as a machine-checked digital specification
- that is not the formal counterpart of some previously published informal material.
+ that is not the formal counterpart of previous informal material.
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This is the System logo: <rlink to="images/crux_177.png">crux_177.png</rlink>