I made an error in a proof

I’ve proved the following (for every funcoids f and g):

Statement \mathrm{up}\,  (f \sqcap^{\mathsf{FCD}} g) \subseteq \bigcup \{ \mathrm{up}\,  (F \sqcap^{\mathsf{FCD}} G) \mid F \in \mathrm{up}\,  f, G \in \mathrm{up}\,  g \} or equivalently: If Z\in\mathrm{up}\,  (f \sqcap^{\mathsf{FCD}} g) then there exists F \in \mathrm{up}\,  f, G \in \mathrm{up}\,  g such that Z\in\mathrm{up}\,  (F \sqcap^{\mathsf{FCD}} G).

But now I’ve noticed that the proof was with an error! So it is again a conjecture.

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