pyphi.conf.formalism.IITConfig#

class pyphi.conf.formalism.IITConfig(version='IIT_4_0_2026', mechanism_phi_measure='GENERALIZED_INTRINSIC_DIFFERENCE', system_phi_measure='INTRINSIC_INFORMATION', specification_measure='GENERALIZED_INTRINSIC_DIFFERENCE', ces_measure='SUM_SMALL_PHI', mechanism_partition_scheme='JOINT_PARTITION_ALL', system_partition_scheme='DIRECTED_SET_PARTITION', system_partition_include_total=False, distinction_phi_normalization='NUM_CONNECTIONS_CUT', background_conditioning='CAUSAL_MARGINALIZATION', relation_computation='ANALYTICAL', assume_partitions_cannot_create_new_concepts=False, shortcircuit_sia=True, shortcircuit_distinctions=True, single_micro_nodes_with_selfloops_have_phi=True, state_tie_resolution='PHI', mip_tie_resolution=<factory>, purview_tie_resolution='PHI', sia_tie_resolution=<factory>)[source]#

Bases: object

IIT-formalism configuration sub-namespace.

Which IIT version computes results and the measures, partition schemes, background conditioning, short-circuiting, and tie-resolution policies it uses. Each attribute documents its own values; the presets pyphi.iit3, pyphi.iit4_2023, and pyphi.iit4_2026 set them together so that a version never runs with options it does not define.

Parameters:

version (str)
mechanism_phi_measure (str)
system_phi_measure (str)
specification_measure (str)
ces_measure (str)
mechanism_partition_scheme (str)
system_partition_scheme (str)
system_partition_include_total (bool)
distinction_phi_normalization (str)
background_conditioning (str)
relation_computation (str)
assume_partitions_cannot_create_new_concepts (bool)
shortcircuit_sia (bool)
shortcircuit_distinctions (bool)
single_micro_nodes_with_selfloops_have_phi (bool)
state_tie_resolution (str)
mip_tie_resolution (Sequence[str])
purview_tie_resolution (str | Sequence[str])
sia_tie_resolution (Sequence[str])

version: str = 'IIT_4_0_2026'#

"IIT_4_0_2026" (default; IIT 4.0 with the intrinsic-information requirement of Mayner et al. 2026), "IIT_4_0_2023" (Albantakis et al. 2023), or "IIT_3_0" (Oizumi et al. 2014). Select a version through a preset (pyphi.iit3, pyphi.iit4_2023, pyphi.iit4_2026) or the formalism= argument of pyphi.analyze(), which also set the measures and schemes the version requires; changing this option alone can leave the others at values the version rejects.

Type:: Which IIT formalism computes results

mechanism_phi_measure: str = 'GENERALIZED_INTRINSIC_DIFFERENCE'#: The distance between a mechanism’s repertoire and its partitioned repertoire, from which a distinction’s φ is computed. IIT 4.0 accepts "GENERALIZED_INTRINSIC_DIFFERENCE" (default) and "INTRINSIC_INFORMATION". IIT 3.0 accepts a distribution distance: "EMD" (the 2014 paper’s earth mover’s distance, set by the iit3 preset), "KLD", "L1", "ENTROPY_DIFFERENCE", "ID", "AID", "PSQ2", or "MP2Q". A version rejects a measure it does not define.

system_phi_measure: str = 'INTRINSIC_INFORMATION'#: How system integrated information φₛ is computed under IIT 4.0. "INTRINSIC_INFORMATION" (default) applies the intrinsic-information requirement, φₛ = min(φ_c, φ_e, ii(s)) (Mayner et al. 2026, Eq. 23); "GENERALIZED_INTRINSIC_DIFFERENCE" gives the 2023 definition, φₛ = min(φ_c, φ_e), without it. IIT 3.0 does not read this option.

specification_measure: str = 'GENERALIZED_INTRINSIC_DIFFERENCE'#: The measure that selects the specified state, the purview or system state with maximal intrinsic information, under IIT 4.0: "GENERALIZED_INTRINSIC_DIFFERENCE" (default), "INTRINSIC_INFORMATION", or "INTRINSIC_SPECIFICATION". IIT 3.0 does not read this option.

ces_measure: str = 'SUM_SMALL_PHI'#: The distance between the unpartitioned and partitioned cause-effect structures, which is IIT 3.0’s system-level Φ: "SUM_SMALL_PHI" (default; the summed φ of the concepts the partition destroys or changes) or "EMD" (the 2014 paper’s earth mover’s distance over concept space, set by the iit3 preset). IIT 4.0 accepts only "SUM_SMALL_PHI".

mechanism_partition_scheme: str = 'JOINT_PARTITION_ALL'#: How a mechanism and its purview are partitioned when a distinction’s irreducibility is evaluated: "JOINT_PARTITION_ALL" (default; every partition of the mechanism and purview into any number of parts, the IIT 4.0 scheme), "JOINT_BIPARTITION" (bipartitions only, the IIT 3.0 scheme, set by the iit3 preset), or "WEDGE_TRIPARTITION" (bipartitions of the mechanism with a third part cut from the purview).

system_partition_scheme: str = 'DIRECTED_SET_PARTITION'#: How a system is partitioned when φₛ is evaluated: "DIRECTED_SET_PARTITION" (default; every set partition of the units with a direction assigned to each part, the IIT 4.0 scheme), "DIRECTED_BIPARTITION" (the IIT 3.0 scheme, set by the iit3 preset), "DIRECTED_BIPARTITION_CUT_ONE", "DIRECTED_BIPARTITION_SEQUENTIAL", "EDGE_CUT_ALL", or "EDGE_CUT_BIDIRECTIONAL". IIT 3.0 accepts only the two directed bipartition schemes. Under IIT 4.0 a non-default scheme computes a well-defined φₛ for that scheme, which is not the papers’ value.

system_partition_include_total: bool = False#: Whether the system partition search includes the total partition, which severs every connection (default False). A single-unit system always includes it, since it has no other partition.

distinction_phi_normalization: str = 'NUM_CONNECTIONS_CUT'#: How a distinction’s φ is normalized before candidate partitions are compared: "NUM_CONNECTIONS_CUT" (default; divided by the number of connections the partition severs, the IIT 4.0 rule) or "NONE" (the raw value, set by the iit3 preset).

background_conditioning: str = 'CAUSAL_MARGINALIZATION'#: How the units outside a candidate system (its background) enter its cause repertoires when the system is a proper subset of the substrate: "CAUSAL_MARGINALIZATION" (default; the background’s past is causally marginalized conditional on the current state, IIT 4.0, Albantakis et al. 2023, Eq. 4) or "CONDITION_CURRENT_STATE" (the background is fixed at its observed current state, the PyPhi 1.x convention, set by the iit3 preset and the only value IIT 3.0 accepts). The effect side conditions the background at its current state under both, and a system that is the whole substrate has no background, so neither is affected.

relation_computation: str = 'ANALYTICAL'#

"ANALYTICAL" (default; relation counts and φ sums in closed form, without enumerating relations, so individual relations cannot be listed) or "CONCRETE" (every relation enumerated, which grows exponentially with the number of distinctions). See pyphi.relations.

Type:: How the relations of a Φ-structure are computed

assume_partitions_cannot_create_new_concepts: bool = False#: IIT 3.0 only. When True, evaluating a system partition considers only the mechanisms that were concepts in the unpartitioned system, which is faster but misses concepts a partition creates. Default False.

shortcircuit_sia: bool = True#: When True (default), IIT 4.0 analyses stop early on detected reducibility: a system whose specified state has no cause or no effect returns a null result without a partition search, and the system- and mechanism-level partition sweeps stop at the first partition with zero integrated information. Computed φ values are unchanged; early stops leave the selection margins undefined, since the remaining partitions were never evaluated. When False, every partition is evaluated and the margins are exact. Does not affect IIT 3.0’s own early exits.

shortcircuit_distinctions: bool = True#: When True (default), evaluating a distinction stops early on detected reducibility: if the effect direction has no candidate purviews, neither search runs, and if the cause’s maximally irreducible purview has φ = 0, the effect search is skipped. The distinction’s φ, the minimum over the two directions, is unchanged, so cause-effect structures are identical either way; only the contents of zero-φ distinctions differ (the skipped direction is a null result without margins or ties). Applies to every formalism.

single_micro_nodes_with_selfloops_have_phi: bool = True#: Whether a single-unit system whose unit has a self-connection can have positive φₛ (default True). When False, such systems have φₛ = 0 by definition, the PyPhi 1.x convention set by the iit3 preset. A single unit without a self-connection has φₛ = 0 regardless.

state_tie_resolution: str = 'PHI'#

a strategy name or a list applied in order, keeping the candidates that are extremal under each. "PHI" (default) keeps the states with maximal φ, and the tie survives in the result if several remain. Other strategies: "NORMALIZED_PHI", "PURVIEW_SIZE", their "NEGATIVE_*" forms, "PARTITION_LEX", and "NONE" (keep all). See Control tie-breaking.

Type:: How a tie among candidate specified states is broken

mip_tie_resolution: Sequence[str]#: How a tie among a mechanism’s candidate partitions at the minimum is broken, a list of strategies applied in order. The default ("NORMALIZED_PHI", "NEGATIVE_PHI") keeps the partitions with the smallest normalized φ, then those with the largest raw φ; the iit3 preset uses ("PHI", "PARTITION_LEX"). See Control tie-breaking.

purview_tie_resolution: str | Sequence[str] = 'PHI'#: How a tie among purviews with maximal φ is broken, a strategy name or a list applied in order. "PHI" (default) keeps every purview at the maximum, so the tie is reported on the result; the iit3 preset uses ("PHI", "PURVIEW_SIZE"), which then keeps the largest purview, the PyPhi 1.x convention. See Control tie-breaking.

sia_tie_resolution: Sequence[str]#: How a tie among system partitions at the minimum is broken, a list of strategies applied in order. The default ("NORMALIZED_PHI", "NEGATIVE_PHI", "PARTITION_LEX") keeps the partitions with the smallest normalized φ, then the largest raw φ, then the first in lexicographic order, so one minimum partition is always selected; a partition_margin of zero on the result records that it was tied. The iit3 preset uses ("PHI", "PARTITION_LEX"). See Control tie-breaking.