Posted 2014-September-21, 05:36
To assign a meaning to the jump to 4♠ I think you also have to consider what a cheaper bid would mean. If you play nothing artificial it makes sense for a jump to game being minimum, and support at a lower level being stronger. If you play that a simple preference could be shorter than expected for a bid at that level, then you can play that a cheap support is shorter than normal, ideally looking for an alternative contract while unable to bid anything better. You can combine these in your examples:
1♠ 2♣, 2♥ 2♠ = only 2 card support, nothing much in diamonds, but willing opener to bid NT if he has only 5 spades and some diamonds
1♠ 2♣, 2♥ 3♠ = 3+ card support, 16+ or thereabouts, encouraging opener to cue if suitable
1♠ 2♣, 2♥ 4♠ = 3+ card support, 13-15 or thereabouts
Similar logic can apply whether opener shows a second suit or not.
On the other hand, if you play something artificial like non-serious 3NT, then any strength hand can support with 2♠, knowing that you can use your artificial convention to deny/show strength at a later stage. That means a jump to 4♠ can carry specific information, such as not just a non-serious hand, but one that has nothing to show should partner otherwise be seeking to cue bid.
The distinction between the auctions depends merely on what the alternatives are.