I have recently started learning logic and I came to know how to translate statement into logical notation using propositional functions and quantifiers. I came across the following problems which are a little bit heavy for me.
We have to translate them into logical notation.
- Some horses are gentle and have been well trained.
- Some horses are gentle only if they have been well trained.
- Some horses are gentle if they have been well trained.
- Any horse is gentle that has been well trained.
- No horse is gentle unless it has been well trained.
- Any horse is gentle if it has been well trained.
- Any horse has been well trained if it is gentle.
- Any horse is gentle if and only if it has been well trained.
- Gentle horses have been well trained.
I have translated them as follows.
Here $H(x)$ ,$G(x)$, $T(x)$ means $x$ is a horse, $x$ is gentle and $x$ is well trained respectively.
($\exists$ $x$) ($H(x)$$\cdot$$G(x)$ $\cdot$$T(x)$).
($\exists$ $x$) ($H(x)$ $\cdot$ ($T(x)$ $\rightarrow$ $G(x)$ )).
($\exists$ $x$) ($H(x)$ $\cdot$ ($G(x)$ $\rightarrow$ $T(x)$ )).
($\forall$ $x$) ($ H(x)$ $\cdot$ $T(x)$ $ \rightarrow$ $ G(x)$ ).
($\forall$ $x$) ($ H(x) $ $\cdot$ $G(x) $ $\rightarrow$ $ T(x)$ ).
Same as 4.
Same as 5.
Unable to translate.(help needed)
Same as 4.
Here $\cdot$ means $and$.
Are my translations right ? If I have done any mistake please let me know.
It's a long question ! So sorry for that. But I am stuck at these problems. Hope to get help. Thanks.
You should swap the answers to 2 and 3:
'Gentle if well-trained' means 'if well-trained then gentle', while 'gentle only if well-trained' means 'if gentle then well-trained'
4 through 9 all need universals ($\forall $)
9 is like 5, not 4
8 is $\forall x (H(x) \rightarrow (G(x) \leftrightarrow T(x)))$