# Tagged Questions

Boolean algebras are structures which behave similar to a power set with complement, intersection and union. Questions regarding Boolean algebras as structures, or regarding functions defined from/to Boolean algebras fit into this tag very nicely. For Boolean logic use the tag propositional logic

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### Axioms for a Heyting Algebra as a Set System (Partial Order Lattice Under Inclusion)

According to the corresponding section in Wikipedia: An element $x$ of a Heyting algebra $H$ is called regular iff $x = \neg y$ for some $y \in H$. Elements $x$ and $y$ of a Heyting algebra ...
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### Is the tensor product of BAOs a kind of extended BAO?

I've been reading "Boolean algebras with operators. Part I." (Jonsson, Tarski) where, given a subalgebra of a Boolean Algebra, they define its perfect extension. As far as I understand it can be ...
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### Why choosing 1 or 0 for the dont care values give different function in a Karnaugh Map?

If I have a Karnaugh Map with dont care values . I can give any dont care the value 1 or 0 depend on my needs. But why if I will choose 1 for the dont care values, it will give me a function $f$ And ...
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### Karnaugh map grouping of element

In Karnaugh map ($4\times 4$) can we group an element that is shared two three different groups. I think answer should be no but I do not know why it is?Can anybody provide a reason in support of this ...
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### Interior algebra vs. Regular open algebra

I know that an interior algebra is a Boolean algebra on which is defined an operation satisfying Kuratowski's axioms for the interior of a set. I recently heard about the regular open algebra, which ...
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### How to rewrite all the boolean operations using if-then-else operator?

Cited by Conditional Term Rewriting Systems: 1st International Workshop Orsay, France, July 8-10, 1987, p. 105 Additional Boolean operations are not needed, because all the usual Boolean ...
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### Boolean expression to check whether a path is a dipath?

Suppose you have an alternating sequence of vertices and egdes $v_0,e_1,v_1,\ldots,e_n,v_n$ for a digraph $G.$ You know that this sequence is at least a path between $s$ vertex and vertex $t$. Does ...
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### Proof Sequences using inference

$(p \land (p \implies q) \land (q \implies r)) \implies r$ It is written slightly different in the text book, but this should be the equivalent form. The book is a bit unclear but I think the author ...
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### Boolean equivalence

Given a boolean formula $\phi$ and an interpretation $x$ that satisfies it, is it possible to come up with a permutation $P$ such that $x$ satisfies $P(\phi)$ but it is computationally hard to ...
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### Is there a book about discrete algebraic structures? [closed]

In German it is called "Diskrete algebraische Strukturen".The literal translation would be discrete algebraic structures, does something like this exist? The course contains the following topics ...
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### How to convert numbers with related bases quickly?

Let: $a = (1011011)_2 = (1123)_4$ There two ways to solve it: Convert the number in base 2 to base 10 then to base $4$. Consider $4 = 2^2$ and group each of two numbers in base $2$ to one in base ...
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### Sum of products expansion of basic Boolean function: $F(x,y) = \bar{y}$

So I have a question about this very basic-looking sum of products expansion. My professor has this particular example in his lecture slides but I can't quite wrap my head around this. I don't ...
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### Clarity on Boolean Algebra and Rings

I'm trying to wrap my head around Abstract Algebra, Boolean rings, and it's a little difficult. So I understand the ring (I believe it's a ring) <ℤ ,x, +, -, 0, 1 > is normal integer arithmetic ...
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### Prove universal gate math

I tried to deal with this question: $$F(a,b,c,d) = (a'+b'+c')\oplus bcd$$ While I asked to prove that F with the constant '$0$' is universal gate. I know that to prove that some function is ...
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### How can I find a DNF and Minimal Form for this boolean expression?

$Q(x,y,z)=(y′\vee z′ \vee 0\vee x′)\wedge1\wedge(z\vee x′\vee 0\vee y\vee z)′\wedge(z′\vee x\vee y\vee z′)$ I'm not supposed to use tables but only proprieties like De Morgan ecc. EDIT: So I ...
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### How to simplify using algebra laws

Simplify the following by using algebra laws. (i) X’.Y’ + X.Y.Z. + X’.Y + X.Y My attempt: X’.Y’ + Y(X.Y.Z + X'Y + X.Y) X’.Y’ + (X.Z + X' + X) X’(X’.Y’ + X') + X.Z + X Y’ + X' + X.Z + X Y’ + X' +...
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### How can I show a set B with 8 elements and two operations (huntington axioms)

How can I show a set B with 8 elements and two operations, such that the axioms of huntington for boolean algebra holds? I found it with set of 2 elemtnts. but can't understand how to start with 8 ...
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### De Morgan's Law Operation order

I have the following boolean logic: $$\overline {\overline {\overline {B+C+D} + \overline {DA}} + \overline {\overline {\overline {A+E} + \overline { B}} + \overline {E}}}$$ I am trying to simplify ...
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### XOR equation with multiplication arrangment

How can I move all the X to one side so the equation will become x=y XOR <somthing>... \begin{align} &2x \oplus y = x \end{align} ...
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### Simplify semi-boolean expression

I'm trying to simplify the following expression: (A == B) OR ( (A > B) AND (A < C) ) Given that B <= C, this is my ...
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### Stuck in Boolean Algebra equation

I have this equation in Boolean Algebra: $x*y*z+x'*y*z+x*y'*z+x*y*z' = y*z+x*z+x*y$ I got this: $= yz(x+x')+xy'z+xyz'$ $= yz+xy'z+xyz'$ And from here I tried multiple things but it goes wrong ...
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### Having trouble with simplifying in Boolean algebra

I want to solve this problem: $$(x . y . z + x . y + x)$$ Which turns into this when you group $x$ $$x . ( yz + y + 1 )$$ What I don't understand is why is there a "1" at the end? ...
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### Using the laws of logic (algebraic version) to show the following equivalences [closed]

I have some questions about algebra and discrete, with using law of logic. I am not sure how to prove the equivalences. Can someone please show me how this works and show the equivalence using the ...
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### How can I prove that $(a + b )\oplus(a + c)$ is not possible to simplify. Or is it?

I was trying to simplify the following expression $(a + b )\oplus(a + c)$, where $+$ is just a simple addition of two numbers and $\oplus$ is a binary xor operation. By simplifying I mean exanding or ...
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### Logic Puzzle (Valid and Invalid Arguments)

I have been given a logic puzzle and I am having a tough time figuring out how to set it up and solve. Here is the puzzle: a) The Statement "If Dr. Jones did not commit the murder then neither Ms. ...
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### Logical limitations of Proofs by Contradiction

In general proofs by contradiction go as follows: Given an arbitrary hypothesis, $\ p \implies q$, we assume $\left(p\implies q\right) = T$, and then we show that by assuming the hypothesis to be ...
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### How to deal with an 8 variable Karnaugh map

I'm reaching back into my high school days trying to remember one of the rules about Karnaugh Maps. I have an 8 variable input, and I remember that I should try and make the selections a big as ...
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### Is there a blackboard bold letter for the set of Boolean numbers? [duplicate]

Is there a symbol (e.g. $\mathbb{B}$) for the special set of Boolean numbers or values; ${0,1}$ or ${True,False}$?
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### Galois field of order 2 constituting a Boolean algebra

We know that the the set $\{0,1\}$ constitutes a Boolean Algebra over the usual $OR$ and $AND$ operations. However, because of the lack of an additive inverse for $1$ this does not produce a Galois ...
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### A proof of maximality of an antichain in a complete Boolean algebra

Suppose $(\mathbf{B},\leqslant)$ is a complete Boolean algebra and let $|\mathbf{B}|=|\gamma|$. Let $C=\langle c_\alpha\mid \alpha<\gamma\rangle$ be a maximal descending chain without a lower bound:...
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### Boolean Expression Simplifying explanation

Currently have worked xz' + x'y + (yz)' Down to z' + x'y + y' Is this its simplest form? METHOD: xz' + x'y + (yz)' -> De-Morgan on (yz)' xz' + x'y + y' + z' -> Commutative xz' + z' + x'y + y' -> ...
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### Do DeMorgan's laws hold for pseudo-complement in Bi-Heyting Algebra?

A textbook says in Heyting Algebra, The pseudo-complement of an element $a$ is denoted as $a^{\ast}$. One of the DeMorgan's law $\left(\vee a_{i}\right)^{\ast}=\wedge a_{i}^{\ast}$ holds ...