SCIP solver control parameters

Create a list of control parameters for the SCIP solver. Parameters are organized into logical groups: output, limits, tolerances, presolving, LP, branching, and heuristics. Any SCIP parameter can also be set directly using its native path via ....

Usage

scip_control(
  verbose = TRUE,
  verbosity_level = 3L,
  display_freq = 100L,
  time_limit = Inf,
  node_limit = -1L,
  stall_node_limit = -1L,
  sol_limit = -1L,
  best_sol_limit = -1L,
  mem_limit = Inf,
  restart_limit = -1L,
  gap_limit = 0,
  abs_gap_limit = 0,
  feastol = 1e-06,
  dualfeastol = 1e-07,
  epsilon = 1e-09,
  presolving = TRUE,
  presolve_rounds = -1L,
  lp_threads = 1L,
  lp_iteration_limit = -1L,
  lp_scaling = TRUE,
  branching_score = "p",
  heuristics_emphasis = "default",
  threads = 1L,
  ...
)

Arguments

verbose: Logical; print solver output. Default TRUE.
verbosity_level: Integer 0–5; verbosity detail. Default 3.
display_freq: Integer; node display frequency. Default 100.
time_limit: Numeric; time limit in seconds. Default Inf.
node_limit: Integer; max nodes. Default -1L.
stall_node_limit: Integer; stall nodes. Default -1L.
sol_limit: Integer; solution limit. Default -1L.
best_sol_limit: Integer; improving solution limit. Default -1L.
mem_limit: Numeric; memory limit in MB. Default Inf.
restart_limit: Integer; restart limit. Default -1L.
gap_limit: Numeric; relative MIP gap. Default 0.
abs_gap_limit: Numeric; absolute gap. Default 0.
feastol: Numeric; feasibility tolerance. Default 1e-6.
dualfeastol: Numeric; dual feasibility tolerance. Default 1e-7.
epsilon: Numeric; zero tolerance. Default 1e-9.
presolving: Logical; enable presolving. Default TRUE.
presolve_rounds: Integer; presolve rounds. Default -1L.
lp_threads: Integer; LP solver threads. Default 1L.
lp_iteration_limit: Integer; LP iteration limit. Default -1L.
lp_scaling: Logical; LP scaling. Default TRUE.
branching_score: Character; score function. Default "p".
heuristics_emphasis: Character; heuristic emphasis. Default "default".
threads: Integer; parallel solving threads. Default 1L. See Parallel section for caveats.
...: Additional SCIP parameters as name-value pairs, using SCIP's native hierarchical parameter paths (e.g., "lp/fastmip" = 1, "conflict/enable" = FALSE). See the SCIP parameter documentation for the full list.

Value

A named list of class "scip_control" with components:

verbose: Logical; verbosity flag.
scip_params: Named list; all parameters as SCIP native paths.

Output

verbose: Logical; print solver output. Default TRUE.
verbosity_level: Integer 0–5; verbosity detail (0 = none, 3 = normal, 5 = full). Default 3. Ignored if verbose = FALSE.
display_freq: Integer; display a status line every this many nodes (-1 = never). Default 100.

Termination Limits

time_limit: Numeric; maximum solving time in seconds. Default Inf (no limit).
node_limit: Integer; maximum number of branch-and-bound nodes. Default -1L (no limit).
stall_node_limit: Integer; nodes without improvement before stopping. Default -1L (no limit).
sol_limit: Integer; stop after finding this many feasible solutions. Default -1L (no limit).
best_sol_limit: Integer; stop after this many improving solutions. Default -1L (no limit).
mem_limit: Numeric; memory limit in MB. Default Inf (no limit).
restart_limit: Integer; maximum restarts. Default -1L (no limit).

Tolerances

gap_limit: Numeric; relative MIP gap tolerance; solver stops when the gap falls below this value. Default 0 (prove optimality).
abs_gap_limit: Numeric; absolute gap between primal and dual bound. Default 0.
feastol: Numeric; feasibility tolerance for LP constraints. Default 1e-6.
dualfeastol: Numeric; dual feasibility tolerance. Default 1e-7.
epsilon: Numeric; absolute values below this are treated as zero. Default 1e-9.

Presolving

presolving: Logical; enable presolving. Default TRUE.
presolve_rounds: Integer; maximum presolving rounds (-1 = unlimited). Default -1L.

LP

lp_threads: Integer; number of threads for LP solver. Default 1L.
lp_iteration_limit: Integer; LP iteration limit per solve (-1 = no limit). Default -1L.
lp_scaling: Logical; enable LP scaling. Default TRUE.

Branching

branching_score: Character; branching score function: "s" (sum), "p" (product), "q" (quotient). Default "p".

Heuristics

heuristics_emphasis: Character; heuristic emphasis setting: "default", "aggressive", "fast", or "off". Default "default".

Parallel

threads: Integer; number of threads for concurrent solving. Default 1L. Note: concurrent solving may require a SCIP build compiled with parallel support (e.g., PARASCIP=true); not all installations provide this.

Examples

## Quick solve with 60-second time limit
ctrl <- scip_control(time_limit = 60)

## Quiet solve with 1% gap tolerance
ctrl <- scip_control(verbose = FALSE, gap_limit = 0.01)

## Aggressive heuristics, no presolving
ctrl <- scip_control(heuristics_emphasis = "aggressive", presolving = FALSE)

## Pass a native SCIP parameter directly
ctrl <- scip_control("conflict/enable" = FALSE, "separating/maxrounds" = 5L)