Hi everyone,

The grades for Exam #3 are posted under Dashboard / OpenLab Gradebook – the exams will be returned on Tuesday. Let me know if you have any questions.

Regards,

Prof. Reitz

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Hi everyone,

The grades for Exam #3 are posted under Dashboard / OpenLab Gradebook – the exams will be returned on Tuesday. Let me know if you have any questions.

Regards,

Prof. Reitz

- How can I write proofs formally and accurately? November 3, 2024Once I was learning elementary linear algebra, my teacher said I should use double arrow($\implies$) in formal proof but I should use single arrow($\rightarrow$) to represent how a matrix is changed during a sequence of EROs, because double arrow is an mathematical sign which means 'implies' while single arrow is just a symbol. However, in […]lIlIllII l
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- Proof that adding witnesses to $S$ keeps $S$ consistent November 3, 2024For context: this may help me resolve this previous post. Definition: for any set of sentences $S$ in the language $L$, define$\def\f{\phi}$ $$w(S) := S\cup\bigg\{\phi[c/x] : (\exists x\phi)\in S\bigg\}$$ in the language $w(L)$ consisting of $L$ with enough constants $c$ added (one such constant $c$ per $\exists x\phi$ statement in $S$ is sufficient). I believe […]Sam
- Proving non-empty sets model the empty theory. November 3, 2024We all love proving a given structure models a given theory but I had a conundrum when needing to show that any non-empty set is a valid structure (in the empty signature). Of course the empty set doesn’t work but how could one prove that for any non-empty $X$, $X\models \varnothing$? My immediate thoughts are […]Lave Cave
- Theorem of Constructive Dilemmas [duplicate] November 2, 2024I saw a theorem in my book that 1) $(p\to q)\wedge (r\to s)\equiv (p\wedge r)\to (q\wedge s)$ and 2) $(p\to q)\wedge (r\to s)\equiv (p\vee r)\to (q\vee s)$. I can prove second item but I can’t prove another one Who can help me? I saw the Constructive Dilemma, but I guess my question is more than […]mahsa
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