Eric Grey attempts to describe the rules for forming a minority government. There are a few points worth mentioning:

• The rules vary among parliamentary democracies. Some democracies, like Germany, require constructive votes of no confidence; in other words, to get rid of an existing government, you have to nominate a new one, which necessarily increases the stability of the system. In some other parliamentary democracies, the government falls if any government proposal is defeated on a party-line vote (i.e. not a “free” vote). Canada generally follows Westminster tradition, where “confidence” is a customary rather than a legal requirement; since only the Prime Minister (well, technically, the sovereign) can dissolve parliament and call elections, essentially this system is equivalent to the German system—although, since a government could only be replaced by a plurality vote, the PM is more likely than not to call new elections before such a vote could take place.
• Minority governments are somewhat more common than one might suspect. Notably, Israel’s government is currently a minority government. Britain and Canada each have had a few since World War II. Interestingly, minority governments are much more common than coalitions in countries with first-past-the-post (plurality) elections.

An interesting study of coalition government, by the way, is Multiparty Government by Michael Laver and Norman Schofield. Laver and Ken Shepsle’s Making and Breaking Governments is probably also worthwhile (from a more game-theoretic perspective, as is Shepsle’s bent), but, alas, I haven’t read it.

Incidentally, I’d appreciate recommendations on a scholarly text (or even a textbook) on Canadian politics, perhaps something comparable to Philip Norton’s The British Polity. For now, it’s just an idle scholarly interest, but maybe an employer one of these decades will be desperate enough to let me teach some comparative courses.