I have two questions that I think are quite related regarding the interpretation of comparatives.
1. Is it necessary to include a より or a 方 expression to convey a comparative?
Suppose you are having a conversation about how the book you just read was too long. You are then asked what you want to do later. You respond:
昨日読んだ本より短いのが買いたい。
I want to buy a shorter book than the one I read yesterday.
(Please bear in mind that I constructed the Japanese sentence above, so it could be wrong in any number of ways. I'd appreciate a correction if required.)
My question is, if you responded with simply:
短い本が買いたい。
would it be interpreted as implying "shorter" (where "shorter" is drawing a comparison to the book previously mentioned in context), or "short" (where "short" is not explicitly compared to anything), or perhaps it is unclear?
Furthermore, is there an alternate way to express the comparison without explicitly stating 「昨日読んだ本」?
2. Do なる expressions imply comparison or must it be explicitly stated?
I'd like to compare the following English sentences:
The road became wide.
The road became wider.
Sentence 1 states that something changed and now the road is wide (as opposed to narrow). Sentence 2 states that something changed and now the road is wider than it used to be. It does not actually state that the road is wide.
As far as I know, both of these sentences would be translated to:
道が広くなった
Is my translation correct for both cases and if so, how could it be altered to differentiate between the two English meanings?