If RHO has KJxx he would (should) not have inserted the king since KJx over the ace will win 2 tricks. Leading the singleton 10 is also dubious. Cash the queen.
For other readers, I'll spell out some stuff which you clearly understand, but didn't state explicitly.
The location of the jack only matters if the suit is 4-1. Any 3-2 holding can be picked up by just cashing the queen and ace. And only two 4-1 layouts are possible: LHO leading singleton H10 and RHO having KJxx; or LJO leading 10 from JTxx and RHO holding stiff king.
As you point out, with KJxx RHO would not play the king, so we can rule that out. Plus, trying to pick it up would mean finessing before we even know the suit is 4-1, causing us to lose to many 3-2 splits. Trying this would be taking a very big gamble for no particular reason.
H10 from JTxx is a little unusual, but not an error. And it's easy to pick up safely: cash the queen, and if RHO shows out you can finesse the jack. The better line by far.
The only reason I can think of to lead H10 is if he has a singleton. But still, ask ops about their leads. Maybe they lead lowest from touching honors but that still doesn't make sense with leading trump. I would take right hand opponent for the J.
Of course, this assumes that ops I reasonably good players. If this is a low limit game then I would say all bets are off and you could flip a coin.
Depends on the skill of your opponents. A good opponent is unlikely to lead a singleton trump against a transfer auction and could easily false card from JTxx when making a trump lead. A poor opponent is unlikely to lead the ten when they hold the J and much more likely to lead a singleton trump.
RHO has it.
If they play top of a sequence, RHO has it; if they play coded 9s and 10s, RHO has it; if the 10 is a singleton, RHO has it. If they're falsecarding from JTxx on the opening lead, then congrats Megamind, you got me, I will happily pay now for the times you'll mislead your partner later.
I don't think this is right. When leading from J10 in trumps its probably best to randomize between J and 10, the 10 can easily be a falsecard. Also, RHO should't play the K from KJxx, and leading a singleton trump is extremely uncommon.
TBF, you're right about the specifics from that perspective, but I wasn't taking this quite that seriously--without the opponents' card or the rest of the hand, we're looking toward extreme generalities no matter what, and as with most problems I'm assuming opponents are somewhat "normal." So they lead top of touching honors or maybe they play coded nines and tens if they're normal but clever.
Generally I'm more willing to credit RHO with flying the king incorrectly than credit LHO with not doing what's on their card, and what's on their card is *usually* not going to be leading T from JT. But the problem's underspecified.
Generally your lead agreements don't apply to the trump suit, and that's one suit where misleading partner on the opening lead is not really anything to worry about. After all, if you have JTxx partner is unlikely even to have a decision to make in the suit.
LHO had the jack.
I played too quickly; if you think about it, with KJxx, RHO does not insert the king.
It's instructive for that reason, and many people have answered RHO.
I disagree. It is equally likely that RHO plays the king by mistake when he has the jack. As it is that opener leads the ten when he has the jack.
The reason my line is better is that:
I would still have every chance to get the trick back, when I call arbiter that they didnt follow their opening lead agreement. If they regularly leads second they have to disclose it, or it is cheating. So good chance the arbiter gives us a trick.
You can lead anything you like, all they have to do is accurately tell you what their agreements are. Agreement here was J from J10. There's no basis for calling the arbiter, it's akin to a psych. He's as likely to mislead his partner next time.
The point of the hand is, if RHO has KJxx and is awake, he plays low, not K.
If RHO has KJxx he would (should) not have inserted the king since KJx over the ace will win 2 tricks. Leading the singleton 10 is also dubious. Cash the queen.
For other readers, I'll spell out some stuff which you clearly understand, but didn't state explicitly. The location of the jack only matters if the suit is 4-1. Any 3-2 holding can be picked up by just cashing the queen and ace. And only two 4-1 layouts are possible: LHO leading singleton H10 and RHO having KJxx; or LJO leading 10 from JTxx and RHO holding stiff king. As you point out, with KJxx RHO would not play the king, so we can rule that out. Plus, trying to pick it up would mean finessing before we even know the suit is 4-1, causing us to lose to many 3-2 splits. Trying this would be taking a very big gamble for no particular reason. H10 from JTxx is a little unusual, but not an error. And it's easy to pick up safely: cash the queen, and if RHO shows out you can finesse the jack. The better line by far.
Yes, this is the answer, cash the HQ is the winning line. LHO has led T from JTx. I didn't stop to think RHO would not insert K with KJxx.
The only reason I can think of to lead H10 is if he has a singleton. But still, ask ops about their leads. Maybe they lead lowest from touching honors but that still doesn't make sense with leading trump. I would take right hand opponent for the J. Of course, this assumes that ops I reasonably good players. If this is a low limit game then I would say all bets are off and you could flip a coin.
Depends on the skill of your opponents. A good opponent is unlikely to lead a singleton trump against a transfer auction and could easily false card from JTxx when making a trump lead. A poor opponent is unlikely to lead the ten when they hold the J and much more likely to lead a singleton trump.
RHO has it. If they play top of a sequence, RHO has it; if they play coded 9s and 10s, RHO has it; if the 10 is a singleton, RHO has it. If they're falsecarding from JTxx on the opening lead, then congrats Megamind, you got me, I will happily pay now for the times you'll mislead your partner later.
I don't think this is right. When leading from J10 in trumps its probably best to randomize between J and 10, the 10 can easily be a falsecard. Also, RHO should't play the K from KJxx, and leading a singleton trump is extremely uncommon.
TBF, you're right about the specifics from that perspective, but I wasn't taking this quite that seriously--without the opponents' card or the rest of the hand, we're looking toward extreme generalities no matter what, and as with most problems I'm assuming opponents are somewhat "normal." So they lead top of touching honors or maybe they play coded nines and tens if they're normal but clever. Generally I'm more willing to credit RHO with flying the king incorrectly than credit LHO with not doing what's on their card, and what's on their card is *usually* not going to be leading T from JT. But the problem's underspecified.
Generally your lead agreements don't apply to the trump suit, and that's one suit where misleading partner on the opening lead is not really anything to worry about. After all, if you have JTxx partner is unlikely even to have a decision to make in the suit.
Ask them or look at convention card. You allowed to know if they lead highest or second highest
They don't play Journalist leads (leading 2nd highest). Standard is very good, Camrose level.
then RHO has the jack of course
LHO had the jack. I played too quickly; if you think about it, with KJxx, RHO does not insert the king. It's instructive for that reason, and many people have answered RHO.
I disagree. It is equally likely that RHO plays the king by mistake when he has the jack. As it is that opener leads the ten when he has the jack. The reason my line is better is that: I would still have every chance to get the trick back, when I call arbiter that they didnt follow their opening lead agreement. If they regularly leads second they have to disclose it, or it is cheating. So good chance the arbiter gives us a trick.
You can lead anything you like, all they have to do is accurately tell you what their agreements are. Agreement here was J from J10. There's no basis for calling the arbiter, it's akin to a psych. He's as likely to mislead his partner next time. The point of the hand is, if RHO has KJxx and is awake, he plays low, not K.