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sav07_homework_1_solution [2007/03/17 19:00] vkuncak |
sav07_homework_1_solution [2007/03/19 12:02] wikiadmin |
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<latex> | <latex> | ||
- | r \circ (s \cap t) \subseteq (r \circ s) \cap (r \circ t) | + | r \circ (s \cap t) \subseteq (r \circ s) \cap (r \circ t) |
</latex> | </latex> | ||
holds. Namely, suppose <latex>(x,z) \in r \circ (s \cap t)</latex>. | holds. Namely, suppose <latex>(x,z) \in r \circ (s \cap t)</latex>. | ||
Then there is a y such | Then there is a y such | ||
- | that <latex>(x,y) \in r</latex> and <latex>(y,z) \in s \cap t</latex>. Therefore, | + | that <latex>(x,y) \in r</latex> and <latex>(y,z) \in s \cap t </latex>. Therefore, |
<latex>(y,z) \in s</latex> and <latex>(y,z) \in t</latex>. From <latex>(x,y) \in r</latex> and <latex>(y,z) \in s</latex> we | <latex>(y,z) \in s</latex> and <latex>(y,z) \in t</latex>. From <latex>(x,y) \in r</latex> and <latex>(y,z) \in s</latex> we | ||
have <latex>(x,z) \in r \circ s</latex>. Similarly, | have <latex>(x,z) \in r \circ s</latex>. Similarly, | ||
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is true and follows from the characterization of wp in Task 4 and the distribution of the right-hand side of implication and universal quantification | is true and follows from the characterization of wp in Task 4 and the distribution of the right-hand side of implication and universal quantification | ||
with respect to conjunction. | with respect to conjunction. | ||
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