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I am reading Giancarlo Guizzardi's PhD thesis Ontological Foundations for Structural Conceptual Models. On p.218 there is an expression I cannot understand. It is

$\forall x,y\ \operatorname{Substantial}(x) \land \operatorname{Substantial}(y) \land (x\mathrel{\int} y)\rightarrow \operatorname{indep}(x,y)$

I believe this is the first time in the thesis the symbol $\int$ has been used in this manner. What does it mean in this context?

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    I can't access the .pdf for whatever reason. How did you get access to the symbol? Copy and paste from the document? Does it render here exactly as it does in the document? – 2017-02-21
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    @Addem can you view this link: http://doc.utwente.nl/50826/1/thesis_Guizzardi.pdf – 2017-02-21

2 Answers 2

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This symbol is defined on page 145 of the linked document.

$( x \mathrel{\int} y ) =_{\text{def}}\neg(x\bullet y)$

On the previous page, $x\bullet y$ is defined by

$(x\bullet y)=_{\text{def}} \exists z(z\leq x\land z\leq y)$

In words, $x\int y$ means that there is no element that is less than or equal to both $x$ and $y$. To use some terminology from comparability theory, it means that the "cones below" $x$ and $y$ (the sets of all points less than or equal to $x$ and $y$ respectively) are disjoint.

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The symbol is defined first on page 145 of the document that you linked.

$x\mathrel{\int}y$ is defined as $\lnot(x\mathrel{\bullet}y)$. And you can track back the definition of $\bullet$ in the few pages before p. 145.