# How many logical symbols can be made for a physical structure like a road-map?

An exercise in my books says that an analogical representation has a physical structure that corresponds directly to the structure of the thing represented. Consider a road map of your country as an analogical representation of facts about your country.

a) Give 5 examples of symbols in the map language.

b) An explicit sentence is one that the creator of the representation actually writes down. An implicit sentence is one that results from explicit sentences because of properties of the analogical representation. Give 3 examples of implicit and explicit sentences in the map language.

This is what I've come up with: Is it right? Is this the kind of structure they're referring to?

http://www.gophoto.it/view.php?i=http://imageshack.us/a/img822/6691/51576159.png#.UGf2e01QGHM

What would the 5 symbols be? I can only think of one- Connected(p1,p2) (p stands for place)

Also, what will the 3 examples of implicit and explicit sentences be? The first one that strikes me is this:

 ∃ p1,p1 Connected(p1,p2) ↔ Connected(p2,p1)

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1. $p$ is a city
2. $p$ has petrol station
3. there is a bridge at point $p$ over a river..