Stockfish Depth 2 the same as Depth 1?

[Hamster]

I noticed that Stockfish Depth 2 has exactly the same evaluation as at Depth 1 (see Arena output below). The number of nodes increases so something appears to be a bit inconsistent. I would have expected Depth 1 to be the evaluation of the net and then Depth 2 the first one where a search is performed but this is not the case it seems. The analysis is performed on the starting position with Stockfish 16 using 1 thread.

Code: Select all

Analysis of C:\Z\StartingPos_1p.epd   
19-Dec-23 16:35:29 Level: 3 Ply
Analyzing engine: SF16

 1 - 0 1                
    Avoid move: 
    Best move (SF16): g2-g4
    Not found in: 00:00
     3/2	00:00.003	         916	305k	+0.26	1.e4
     3/2	00:00.003	         916	305k	+0.18	1.e3
     3/2	00:00.003	         916	305k	+0.07	1.h3
     3/2	00:00.003	         916	305k	+0.04	1.d3
     3/2	00:00.003	         916	305k	+0.04	1.c4
     3/3	00:00.003	         916	305k	+0.03	1.c3  e5
     3/2	00:00.003	         916	305k	+0.02	1.Nf3
     3/3	00:00.003	         916	305k	-0.06	1.a4  e5
     3/2	00:00.003	         916	305k	-0.08	1.d4
     3/3	00:00.003	         916	305k	-0.25	1.b3  Nf6
     3/3	00:00.003	         916	305k	-0.39	1.h4
     3/3	00:00.003	         916	305k	-0.39	1.Nh3  e6
     3/3	00:00.003	         916	305k	-0.60	1.a3  d5
     3/3	00:00.003	         916	305k	-0.63	1.f3
     3/3	00:00.003	         916	305k	-0.65	1.Na3
     3/3	00:00.003	         916	305k	-0.70	1.b4
     3/3	00:00.003	         916	305k	-0.72	1.Nc3  e5
     3/3	00:00.003	         916	305k	-1.04	1.f4  Nh6
     3/3	00:00.003	         916	305k	-1.15	1.g4  d5
     3/3	00:00.003	         916	305k	-1.24	1.g3  d5
   ---------------------------------------------------------------------------
     2/2	00:00.001	         457	457k	+0.02	1.Nf3
     2/2	00:00.001	         457	457k	-0.08	1.d4
     2/2	00:00.001	         457	457k	-0.08	1.e4
     2/2	00:00.001	         457	457k	-0.16	1.e3
     2/2	00:00.001	         457	457k	-0.25	1.a3
     2/2	00:00.001	         457	457k	-0.28	1.c3
     2/2	00:00.001	         457	457k	-0.30	1.g3
     2/2	00:00.001	         457	457k	-0.30	1.d3
     2/2	00:00.001	         457	457k	-0.32	1.h3
     2/2	00:00.001	         457	457k	-0.33	1.Nh3
     2/2	00:00.001	         457	457k	-0.35	1.Nc3
     2/2	00:00.001	         457	457k	-0.38	1.c4
     2/2	00:00.001	         457	457k	-0.39	1.h4
     2/2	00:00.001	         457	457k	-0.39	1.a4
     2/2	00:00.001	         457	457k	-0.46	1.b3
     2/2	00:00.001	         457	457k	-0.52	1.f4
     2/2	00:00.001	         457	457k	-0.63	1.f3
     2/2	00:00.001	         457	457k	-0.65	1.Na3
     2/2	00:00.001	         457	457k	-0.70	1.b4
     2/2	00:00.001	         457	457k	-0.78	1.g4
   ---------------------------------------------------------------------------
     1/1	00:00.001	         247	247k	+0.02	1.Nf3
     1/1	00:00.001	         247	247k	-0.08	1.d4
     1/1	00:00.001	         247	247k	-0.08	1.e4
     1/1	00:00.001	         247	247k	-0.16	1.e3
     1/1	00:00.001	         247	247k	-0.25	1.a3
     1/1	00:00.001	         247	247k	-0.28	1.c3
     1/1	00:00.001	         247	247k	-0.30	1.g3
     1/1	00:00.001	         247	247k	-0.30	1.d3
     1/1	00:00.001	         247	247k	-0.32	1.h3
     1/1	00:00.001	         247	247k	-0.33	1.Nh3
     1/1	00:00.001	         247	247k	-0.35	1.Nc3
     1/1	00:00.001	         247	247k	-0.38	1.c4
     1/1	00:00.001	         247	247k	-0.39	1.h4
     1/1	00:00.001	         247	247k	-0.39	1.a4
     1/1	00:00.001	         247	247k	-0.46	1.b3
     1/1	00:00.001	         247	247k	-0.52	1.f4
     1/1	00:00.001	         247	247k	-0.63	1.f3
     1/1	00:00.001	         247	247k	-0.65	1.Na3
     1/1	00:00.001	         247	247k	-0.70	1.b4
     1/1	00:00.001	         247	247k	-0.78	1.g4
     

[syzygy]

Did you try 1 whole position?

[Hamster]

I am not sure what you mean by "1 whole position" but I did look a bit more and this effect only seems to exist for White moves. If Black is to move than the evaluations of Depth 1 and Depth 2 differ as expected, still a bit odd. I wonder if there is a dedicated Stockfish forum.