https://youtu.be/wLUaar4_WQM

1. ήʔϜཧ࿦#4*$ୈճ
த‫ࢢंݹ‬৔ͱϨϞϯ

2. 1. ʮத‫ࢢंݹ‬৔ͱϨϞϯʯͰͷ
‫׬‬શϕΠδΞϯ‫ߧۉ‬Λ֬ೝ
ຊಈըͷ໨త

3. 1. ಈతͳ৘ใෆ‫׬‬උήʔϜͷྫ
(1)த‫ࢢंݹ‬৔ͷϞσϧ
(2)த‫ࢢंݹ‬৔ͷ෼ੳ
໨࣍

4. Example:Dynamic games with Incomplete information
ಈతͳ৘ใෆ‫׬‬උήʔϜͷྫ

5. த‫ࢢंݹ‬৔ͷϞσϧ
৘ใෆ‫׬‬උͷϞσϧΛ༻͍ͯ
ΞΧϩϑʹΑͬͯ෼ੳ͞Εͨ
Akerlof, George A. (1970),
“The Market for ‘Lemons’: Quality Uncertainty and the Market Mechanism.”
Quarterly Journal of Economics, 84(3), pp. 488-500.
ˎLemons͸࣭ͷѱ͍த‫ंݹ‬ͷ͜ͱΛࢦ͢
࣋ͪࠐ·ͳ͍ 065
࣋ͪࠐΉ */
ߴ )
௿ -

6. த‫ࢢंݹ‬৔ͷϞσϧ
ंͷॴ༗ऀ͕ंΛചΔ͜ͱΛߟ͑Δ
σΟʔϥʔ͸࣋ͪࠐ·Εͨंʹର͠
ʮߴ͍Ձ֨Λ͚ͭΔʯ
·ͨ͸ʮ௿͍Ձ֨Λ͚ͭΔʯΛબͿͱ͢Δ
͜͜Ͱंͷॴ༗ऀ͸ं͕ྑ͍ঢ়ଶ
ѱ͍ঢ়ଶͲͪΒͳͷ͔Θ͔Δ΋ͷͱ͠
Ұํ
σΟʔϥʔ͸Θ͔Βͳ͍΋ͷͱ͢Δ
࣋ͪࠐ·ͳ͍ 065
࣋ͪࠐΉ */
ߴ )
௿ -

7. த‫ࢢंݹ‬৔ͷϞσϧ
ల։‫ܗ‬ද‫ݱ‬
࣋ͪࠐ·ͳ͍ 065
N
࣋ͪࠐΉ */
ߴ )
௿ -
1
1
2
2
*/
065
ࣗવ
ྑ͍ (PPE
ѱ͍ #BE
(2, 0)
(3, 2)
(1, 0)
(3, − 1)
(1, 2)
(0, 0)
ߴ )
௿ -
ྑ͍ंࣗମՁ஋͋Γ
‫͍ྑʹ͍ޓ‬औҾ
ചΓखṶ͚
ଥ౰ͳऔҾ
ѱ͍ं͸Ձ஋ͳ͠
ച٫ͤͣʹ࣋ͪ‫ؼ‬Γ
1
2
1
2
٬‫཰֬؍‬

8. த‫ࢢंݹ‬৔ͷϞσϧ
ల։‫ܗ‬ද‫ݱ‬
࣋ͪࠐ·ͳ͍ 065
N
࣋ͪࠐΉ */
ߴ )
௿ -
1
1
2
2
*/
065
ࣗવ
ྑ͍ (PPE
ѱ͍ #BE
(2, 0)
(3, 2)
(1, 0)
(3, − 1)
(1, 2)
(0, 0)
ߴ )
௿ -
ྑ͍ंࣗମՁ஋͋Γ
‫͍ྑʹ͍ޓ‬औҾ
ചΓखṶ͚
ଥ౰ͳऔҾ
ѱ͍ं͸Ձ஋ͳ͠
ച٫ͤͣʹ࣋ͪ‫ؼ‬Γ
1
2
1
2
٬‫཰֬؍‬

9. த‫ࢢंݹ‬৔ͷϞσϧ
ల։‫ܗ‬ද‫ݱ‬
࣋ͪࠐ·ͳ͍ 065
N
࣋ͪࠐΉ */
ߴ )
௿ -
1
1
2
2
*/
065
ࣗવ
ྑ͍ (PPE
ѱ͍ #BE
(2, 0)
(3, 2)
(1, 0)
(3, − 1)
(1, 2)
(0, 0)
ߴ )
௿ -
ྑ͍ंࣗମՁ஋͋Γ
‫͍ྑʹ͍ޓ‬औҾ
ചΓखṶ͚
ଥ౰ͳऔҾ
ѱ͍ं͸Ձ஋ͳ͠
ച٫ͤͣʹ࣋ͪ‫ؼ‬Γ
1
2
1
2
٬‫཰֬؍‬

10. த‫ࢢंݹ‬৔ͷϞσϧ
ల։‫ܗ‬ද‫ݱ‬
࣋ͪࠐ·ͳ͍ 065
N
࣋ͪࠐΉ */
ߴ )
௿ -
1
1
2
2
*/
065
ࣗવ
ྑ͍ (PPE
ѱ͍ #BE
(2, 0)
(3, 2)
(1, 0)
(3, − 1)
(1, 2)
(0, 0)
ߴ )
௿ -
ྑ͍ंࣗମՁ஋͋Γ
‫͍ྑʹ͍ޓ‬औҾ
ചΓखṶ͚
ଥ౰ͳऔҾ
ѱ͍ं͸Ձ஋ͳ͠
ച٫ͤͣʹ࣋ͪ‫ؼ‬Γ
1
2
1
2
٬‫཰֬؍‬

11. த‫ࢢंݹ‬৔ͷϞσϧ
ల։‫ܗ‬ද‫ݱ‬
࣋ͪࠐ·ͳ͍ 065
N
࣋ͪࠐΉ */
ߴ )
௿ -
1
1
2
2
*/
065
ࣗવ
ྑ͍ (PPE
ѱ͍ #BE
(2, 0)
(3, 2)
(1, 0)
(3, − 1)
(1, 2)
(0, 0)
ߴ )
௿ -
ྑ͍ंࣗମՁ஋͋Γ
‫͍ྑʹ͍ޓ‬औҾ
ചΓखṶ͚
ଥ౰ͳऔҾ
ѱ͍ं͸Ձ஋ͳ͠
ച٫ͤͣʹ࣋ͪ‫ؼ‬Γ
1
2
1
2
٬‫཰֬؍‬

12. த‫ࢢंݹ‬৔ͷϞσϧ
ల։‫ܗ‬ද‫ݱ‬
࣋ͪࠐ·ͳ͍ 065
N
࣋ͪࠐΉ */
ߴ )
௿ -
1
1
2
2
*/
065
ࣗવ
ྑ͍ (PPE
ѱ͍ #BE
(2, 0)
(3, 2)
(1, 0)
(3, − 1)
(1, 2)
(0, 0)
ߴ )
௿ -
ྑ͍ंࣗମՁ஋͋Γ
‫͍ྑʹ͍ޓ‬औҾ
ചΓखṶ͚
ଥ౰ͳऔҾ
ѱ͍ं͸Ձ஋ͳ͠
ച٫ͤͣʹ࣋ͪ‫ؼ‬Γ
1
2
1
2
٬‫཰֬؍‬

13. த‫ࢢंݹ‬৔ͷ෼ੳ
ϕΠδΞϯήʔϜ
࣋ͪࠐ·ͳ͍ 065
N
࣋ͪࠐΉ */
ߴ )
௿ -
1
1
2
2
*/
065
ࣗવ
ྑ͍ (PPE
ѱ͍ #BE
(2, 0)
(3, 2)
(1, 0)
(3, − 1)
(1, 2)
(0, 0)
ߴ )
௿ -
1
2
1
2
̍ʘ )JHI -PX
065065
065*/
*/065
*/*/

14. த‫ࢢंݹ‬৔ͷ෼ੳ
ϕΠδΞϯήʔϜ
࣋ͪࠐ·ͳ͍ 065
N
࣋ͪࠐΉ */
ߴ )
௿ -
1
1
2
2
*/
065
ࣗવ
ྑ͍ (PPE
ѱ͍ #BE
(2, 0)
(3, 2)
(1, 0)
(3, − 1)
(1, 2)
(0, 0)
ߴ )
௿ -
1
2
1
2
̍ʘ )JHI -PX
065065
065*/
*/065
*/*/

15. த‫ࢢंݹ‬৔ͷ෼ੳ
ϕΠδΞϯήʔϜ
࣋ͪࠐ·ͳ͍ 065
N
࣋ͪࠐΉ */
ߴ )
௿ -
1
1
2
2
*/
065
ࣗવ
ྑ͍ (PPE
ѱ͍ #BE
(2, 0)
(3, 2)
(1, 0)
(3, − 1)
(1, 2)
(0, 0)
ߴ )
௿ -
1
2
1
2
̍ʘ )JHI -PX
065065
065*/
*/065
*/*/

16. த‫ࢢंݹ‬৔ͷ෼ੳ
‫׬‬શϕΠδΞϯ‫ߧۉ‬
࣋ͪࠐ·ͳ͍ 065
N
࣋ͪࠐΉ */
ߴ )
௿ -
1
1
2
2
*/
065
ࣗવ
ྑ͍ (PPE
ѱ͍ #BE
(2, 0)
(3, 2)
(1, 0)
(3, − 1)
(1, 2)
(0, 0)
ߴ )
௿ -
1
2
1
2
ϓϨΠϠʔͷ ্ͷ৴೦Λ
u2
1 (r,1 − r)
r
1 − r
u2
1
u1
1
u1
2

17. த‫ࢢंݹ‬৔ͷ෼ੳ
‫׬‬શϕΠδΞϯ‫ߧۉ‬
࣋ͪࠐ·ͳ͍ 065
N
࣋ͪࠐΉ */
ߴ )
௿ -
1
1
2
2
*/
065
ࣗવ
ྑ͍ (PPE
ѱ͍ #BE
(2, 0)
(3, 2)
(1, 0)
(3, − 1)
(1, 2)
(0, 0)
ߴ )
௿ -
1
2
1
2
r
1 − r
u2
1
ϓϨΠϠʔͷ ্ͷ৴೦Λ
͜ͷ৴೦ͷ΋ͱஞ࣍߹ཧతͳߦಈ͸
u2
1 (r,1 − r)
H2
(r, b1
, b2
)
= r{2b2
+ 0(1 − b2
)} + (1 − r){(−1)b2
+ 2(1 − b2
)}
= (5r − 3)b2
+ 2(1 − r)
b2
r
1
1
0
3
5
ͷ஋ʹΑΓ࠷దͳߦಈ ͕มԽ
r b2
u1
1
u1
2
b2
1 − b2

18. த‫ࢢंݹ‬৔ͷ෼ੳ
‫׬‬શϕΠδΞϯ‫ߧۉ‬
࣋ͪࠐ·ͳ͍ 065
N
࣋ͪࠐΉ */
ߴ )
௿ -
1
1
2
2
*/
065
ࣗવ
ྑ͍ (PPE
ѱ͍ #BE
(2, 0)
(3, 2)
(1, 0)
(3, − 1)
(1, 2)
(0, 0)
ߴ )
௿ -
1
2
1
2
r
1 − r
u2
1
ϓϨΠϠʔͷ ্ͷ
ஞ࣍߹ཧతͳߦಈ͸
u1
1
H1
(r, b1
, b2
)
= b1
1{3b2
+ 1(1 − b2
)} + 2(1 − b1
1)
= (2b2
− 1)b1
1 + 2
b1
1
b2
1
1
0
1
2
u1
1
u1
2
b2
1 − b2
1 − b1
1
b1
1 ͷ஋ʹΑΓ࠷దͳߦಈ ͕มԽ
b2
b1
1

19. த‫ࢢंݹ‬৔ͷ෼ੳ
‫׬‬શϕΠδΞϯ‫ߧۉ‬
࣋ͪࠐ·ͳ͍ 065
N
࣋ͪࠐΉ */
ߴ )
௿ -
1
1
2
2
*/
065
ࣗવ
ྑ͍ (PPE
ѱ͍ #BE
(2, 0)
(3, 2)
(1, 0)
(3, − 1)
(1, 2)
(0, 0)
ߴ )
௿ -
1
2
1
2
r
1 − r
u2
1
ϓϨΠϠʔͷ ্ͷ
ஞ࣍߹ཧతͳߦಈ͸
ͷ஋ʹؔΘΒͣ
u1
2
H1
(r, b1
, b2
)
= b1
2{3b2
+ 1(1 − b2
)} + 0(1 − b1
2)
= (2b2
+ 1)b1
2
b2
b1
2 = 1
u1
1
u1
2
b2
1 − b2
1 − b1
1
b1
1
1 − b1
2
b1
2

20. த‫ࢢंݹ‬৔ͷ෼ੳ
‫׬‬શϕΠδΞϯ‫ߧۉ‬
࣋ͪࠐ·ͳ͍ 065
N
࣋ͪࠐΉ */
ߴ )
௿ -
1
1
2
2
*/
065
ࣗવ
ྑ͍ (PPE
ѱ͍ #BE
(2, 0)
(3, 2)
(1, 0)
(3, − 1)
(1, 2)
(0, 0)
ߴ )
௿ -
1
2
1
2
r
1 − r
u2
1
ϓϨΠϠʔͷ ্ͷ
ஞ࣍߹ཧతͳߦಈ͸
ͷ஋ʹؔΘΒͣ
u1
2
H1
(r, b1
, b2
)
= b1
2{3b2
+ 1(1 − b2
)} + 0(1 − b1
2)
= (2b2
+ 1)b1
2
b2
b1
2 = 1
u1
1
u1
2
b2
1 − b2
1 − b1
1
b1
1
0
1

21. த‫ࢢंݹ‬৔ͷ෼ੳ
‫׬‬શϕΠδΞϯ‫ߧۉ‬
࣋ͪࠐ·ͳ͍ 065
N
࣋ͪࠐΉ */
ߴ )
௿ -
1
1
2
2
*/
065
ࣗવ
ྑ͍ (PPE
ѱ͍ #BE
(2, 0)
(3, 2)
(1, 0)
(3, − 1)
(1, 2)
(0, 0)
ߴ )
௿ -
1
2
1
2
r
1 − r
u2
1
ϓϨΠϠʔͷ ্ͷ
੔߹తͳ৴೦͸
u2
1
r* =
1
2
b1
1
1
2
b1
1 +
1
2
1
=
b1
1
b1
1 + 1
u1
1
u1
2
b2
1 − b2
1 − b1
1
b1
1
0
1

22. த‫ࢢंݹ‬৔ͷ෼ੳ
‫׬‬શϕΠδΞϯ‫ߧۉ‬
࣋ͪࠐ·ͳ͍ 065
N
࣋ͪࠐΉ */
ߴ )
௿ -
1
1
2
2
*/
065
ࣗવ
ྑ͍ (PPE
ѱ͍ #BE
(2, 0)
(3, 2)
(1, 0)
(3, − 1)
(1, 2)
(0, 0)
ߴ )
௿ -
1
2
1
2
u2
1
u1
1
u1
2
b2
1 − b2
1 − b1
1
b1
1
0
1
r* =
b1
1
b1
1 + 1
b2
r
1
1
0
3
5
b1
1
b2
1
1
0
1
2
1
2
r* =
b1
1
b1
1 + 1
≤
1
2
͕࠷ద൓ԠͷϖΞ
b1
1 = 0, b2
= 0

23. த‫ࢢंݹ‬৔ͷ෼ੳ
‫׬‬શϕΠδΞϯ‫ߧۉ‬
࣋ͪࠐ·ͳ͍ 065
N
࣋ͪࠐΉ */
ߴ )
௿ -
1
1
2
2
*/
065
ࣗવ
ྑ͍ (PPE
ѱ͍ #BE
(2, 0)
(3, 2)
(1, 0)
(3, − 1)
(1, 2)
(0, 0)
ߴ )
௿ -
1
2
1
2
u2
1
u1
1
u1
2
0
1
1
0
0
1
r* = 0 b2
r
1
1
0
3
5
b1
1
b2
1
1
0
1
2
1
2
r* =
b1
1
b1
1 + 1
≤
1
2
͕࠷ద൓ԠͷϖΞ
b1
1 = 0, b2
= 0
0
1
1

24. த‫ࢢंݹ‬৔ͷ෼ੳ
৘ใෆ‫׬‬උͷϞσϧΛ༻͍ͯ
ΞΧϩϑʹΑͬͯ෼ੳ͞Εͨ
Akerlof, George A. (1970),
“The Market for ‘Lemons’: Quality Uncertainty and the Market Mechanism.”
Quarterly Journal of Economics, 84(3), pp. 488-500.
த‫ࢢंݹ‬৔ʹ͸࣭ͷѱ͍ঢ়ଶͷं͔͠ࢢ৔ʹग़ճΒͳ͍͜ͱʹͳΔ͜ͷ‫ݱ‬৅Λ‫ٯ‬બൈͱ‫Ϳݺ‬
࣋ͪࠐ·ͳ͍ 065
࣋ͪࠐΉ */
ߴ )
௿ -

25. ήʔϜཧ࿦#4*$ୈճ
த‫ࢢंݹ‬৔ͱϨϞϯ
‫׬‬
ήʔϜཧ࿦#4*$ୈճʹͭͮ͘
See you next timeʂ