Difficult Predicate Logic Symbolization

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Homework Help Overview

The discussion revolves around symbolizing a complex sentence in predicate logic involving elves, their characteristics (mean or friendly), and their behavior (biting when provoked or not). The original poster presents an attempt at symbolization using specific predicates and variables.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • Participants explore different notations for clarity and question the necessity of certain components in the original symbolization. There is a discussion about the implications of provocation and whether the characteristics of being mean or friendly are mutually exclusive.

Discussion Status

Some participants have provided alternative approaches and suggestions for simplification, while the original poster expresses ongoing confusion. The conversation is active with attempts to clarify the logic and notation used.

Contextual Notes

There is an indication that the original poster is uncertain about the appropriateness of the forum for this topic. Additionally, assumptions about the relationships between the characteristics of the elves and their behaviors are being questioned.

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Homework Statement



I do not know if this is the right forum or subforum for this kind of topic. So if it is not, I apologize in advance.Symbolize the following sentence:

Given that some mean elf will bite and some friendly one will too, the mean ones will bite whether or not provoked but the friendly ones will bite only if provoked.

Homework Equations



Fx: x is friendly
Gx: x is mean
Hx: x is an elf
Ix: x will bite
Jx: x is provoked

The Attempt at a Solution

This is my attempt and to me it seems right, but I could be missing one tiny simple thing.

∃x∃y(((Hx∧Gx∧Ix)∧(Fy∧Hy∧Iy))→((Jx∨∼Jx)→Ix)∧(Iy→Jy))
 
Last edited:
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Ok, given I'm actually not that good at these...

First for clarity and to simplify reading, I would probably use the folliwng nonmenclature (some good notation can simplify/clarify your problem immensly)
E-Elf, M-Mean, F-Friendly, P-Provoked, B-Bites

if I look at yours
∃x∃y(((Ex∧Mx∧Bx)∧(Fy∧Ey∧By))→((Px∨∼Px)→Bx)∧(By→Py) )

first I note (Px∨∼Px) is always true, as the elf is either provoked or not, so I'm not sure you need that? so it becomes
∃x∃y(((Ex∧Mx∧Bx)∧(Fy∧Ey∧By))→(Bx)∧(By→Py)

then I'd say both Bx and By are assumed true in the LHS, so are always true when the RHS is evaluated? so it becomes
∃x∃y(((Ex∧Mx∧Bx)∧(Fy∧Ey∧By))→Py

Which doesn't tell us a heap... and then I would ask if you really need the x and the y to cover the two cases when the elf is mean or friendly, and whether friendly and mean were mutually exclusive so you could you assume friendly = (not mean), and the "for exists" only shows its true for some x and y, not all of them...

So I was thinking you could simplify your approach by dropping the x and ys, and looking at it as follows...

Given that some mean elf will bite and some friendly one will too,
(is an elve and bites)
the mean ones will bite whether or not provoked but the friendly ones will bite only if provoked.
(implies either mean or friendly and provoked)
 
Last edited:
Thanks for your time lanedance, but I am still stuck!
 
ok how about looking at the first bracketed comment, how would you write that?
 

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