An interesting surrender!

Player beside me playing anchor and two hands has a hard 18 on his first hand and a hard 15 on his second and anchor hand. The dealer has a face card and no hole card. The player expects a face card so he surrenders the 15 and the dealer draws the face and he loses both hands. Looking at the 15 hand on its own, the correct play is to surrender but when you take into account your other 18 hand you are now putting that hand at risk. Should one resist surrender in this instance?

Surrendering the 15 hand does not place any additional risk on the 18 hand. The decision for each hand has to be decided independently of the other, just as if the two hands were played by separate players.

Are the cards marked, or is he cheating in some other way? If not, the hands should each be played on their own merit, exactly as Stealth Bomber said.

ETF

if hit and as every third card is usually a face, on average, it causes concern for the 18 hand. If the player is right, and draws a face, he's temporarily saved his other hand. If he draws a helpful card to the 15, he may save this hand and still come out even if losing the 18 hand.

jomoats,

Consider these cases:

(A) If he stands on both, he'll lose both because the dealer will draw the face that the player somehow "knows" is coming, and the dealer's resulting 20 will beat both hands. EV here is -100%.

(B) If he surrenders both, he loses a total of one bet, so his overall EV is -50%.

(C) If as you suggest he stands on the 18 and hits the 15 (to absorb the face that he "knows" is coming), then he'll first lose one bet (the 15 he busts) and still be left with 18 vs. X, which is a -EV hand (roughly -20% for 6D, NHC).
(C1) If he subsequently wins the 18 vs. X hand, he'll break even overall, so his EV will be 0%.
(C2) If he pushes, he'll lose a total of one bet, for an EV of -50%. (C3) If he loses, his EV will be -100%.
However, since 18 vs. X is a -EV hand, on average he'll lose more often than he wins, so on average his EV will be between the results for (C2) and (C3): in other words, his EV will be below -50%.

Therefore, when he "knows" a face is coming in this situation, his highest EV (least negative) play is (B), surrender both hands.

Of course, you haven't told us how he "knows" a face card is coming next!

Hope this makes it clear to you!

Dog Hand

If the player is right, and draws a face, he's temporarily saved his other hand.

What if he is wrong and that causes himself to lose the 18 hand?

Suppose there are only three cards remaining: 2, 6, 10. There are 6 equally likely permuations of their order coming out of the deck. Following is a list of the results for the 18 hand he hits the 15 hand.

Player hits 15
2, 6, 10: win
2, 10, 6: lose
6, 2, 10: win
6, 10, 2: lose
10, 2, 6: push
10, 6, 2: push

Now what happens if he surrender:

Player surrenders 15
2, 6, 10: push
2, 10, 6: win
6, 2, 10: push
6, 10, 2: win
10, 2, 6: lose
10, 6, 2: lose

Notice that in either case, the results are the same: win twice, lose twice, and push twice. So the action on the 15 hand has no affect on the EV of the 18 hand. This is true for any combination of remaining cards. You have already conceded the best action for the 15 hand is to surrender, therefore, the best EV for both hands in combination is also to surrender.

I get the player even hitting the fifteen. Winning 5 units and losing 5 units. Surrendering the 15 I get the player losing 5 units and winning 2 units.

I get the player even hitting the fifteen. Winning 5 units and losing 5 units.

The point is that how you play the 15 hand has no affect on the EV of the 18 hand. Yes, in the previous example, it is better to hit 15 than to surrender, but that does not hold for all permutations. What does hold is that the EV of the 18 hand does not change based on the actions of the other hand.

If I change the 6 in my previous example to a 7, for instance, by hitting the 15 hand you would win 1 and lose 5. If you surrender, you lose only 6 1/2 bets. In either case, the 18 hand wins 3 and loses 3.

but once the cards are in motion I would think the EV would continually change, even though I'm not aware if it's favorable or not. Maybe only card counters should surrender.

... after you sort it allllllllll out, each hand should be played on its own merits. Whatever card you THINK you're going to get could just as easily be switched with the next card, or the card after that, or ...

Panama Rick is right, as usual, except when he disagrees with me. Even then he's mostly right. ;)

ETF