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Terminal: run. Derivation Graphs: (left-to-right) compact / full; (top-down) full / compact.

Help: blue = parse inside. Abbr.: WS: Workspace; Initial WS: initial heads for Merge after LEX lookup.

WS n, n = 1,2,... for intermediate stages after Initial WS. Final WS: when WS items converge on a single SO.
Bracketing: {...} (Merge). {...} (FormSet). At Spellout, {...} indicates free word order. [word] indicates word is optionally present.
Head Hd_{selection/features}, e.g. p_θ = predicate head p that seeks a θ-relevant (θR) IA from the WS. p_θ is a θ-seeker (θS).
v_see:θ:pst = head v has complement see, a θR EA from the WS and TNS. v is also a θS.
INFL seeks θR from its complement (not the WS).
Complementizer C comes in different flavors wrt. Force, .e.g. declarative C, interrogative C_Q and relative clause head C_rel.
Features, e.g. TNS pres/pst or DET the/a (shorthand for a bundle of semantic features).
Note: φ-features, e.g. 1sg, appear only at Spellout. Some words do not project, turn into features, e.g. determiners.

Words: who sees John

Initial WS 1: John see_θ v_see:_θ:_pres INFL_v:_3sg who

WS 1: {see_θ, John} v_see:_θ:_pres INFL_v:_3sg who

WS 2: {v_see:_θ:_pres, {see_θ, John}} INFL_v:_3sg who

WS 3: {who, {v_see:_θ:_pres, {see_θ, John}}} INFL_v:_3sg

WS 4: {INFL_v:_3sg, {who, {v_see:_θ:_pres, {see_θ, John}}}}

Final WS: {C_Q:_left(who), {INFL_v:_3sg, {who, {v_see:_θ:_pres, {see_θ, John}}}}}

INT/EXT: {C_Q:_left(who), {INFL_v:_3sg, {who, {v_see:_θ:_pres, {see_θ, John}}}}}

EXT: who →→ 3sg pres see John

Spellout: who 3sg pres see John

Spellout: who sees John

Parse found: who →→ 3sg pres see John

WS 1: {see_θ, John} v_see:_θ:_pres INFL_v:_3sg who

WS 2: {v_see:_θ:_pres, {see_θ, John}} INFL_v:_3sg who [gray]

WS 3: {John, {v_see:_θ:_pres, {see_θ, John}}} INFL_v:_3sg who

WS 4: {INFL_v:_3sg, {John, {v_see:_θ:_pres, {see_θ, John}}}} who

WS 1: {see_θ, who} John v_see:_θ:_pres INFL_v:_3sg

WS 2: {v_see:_θ:_pres:_box(who), {see_θ, who}} John INFL_v:_3sg

WS 3: {John, {v_see:_θ:_pres:_box(who), {see_θ, who}}} INFL_v:_3sg

WS 4: {INFL_v:_3sg, {John, {v_see:_θ:_pres:_box(who), {see_θ, who}}}}

Final WS: {C_Q:_left(who), {INFL_v:_3sg, {John, {v_see:_θ:_pres:_box(who), {see_θ, who}}}}}

INT/EXT: {C_Q:_left(who), {INFL_v:_3sg, {John, {v_see:_θ:_pres:_box(who), {see_θ, who}}}}}

EXT: who 3sg pres see →→ John 3sg pres see

Spellout: who 3sg pres do John see

Spellout: who does John see

Blocked: inconsistent with input!

WS 1: {see_θ, who} John v_see:_θ:_pres INFL_v:_3sg

WS 2: {v_see:_θ:_pres:_box(who), {see_θ, who}} John INFL_v:_3sg [gray]

WS 3: {who, {v_see:_θ:_pres:_box(who), {see_θ, who}}} John INFL_v:_3sg

WS 4: {INFL_v:_3sg, {who, {v_see:_θ:_pres:_box(who), {see_θ, who}}}} John

WS 1: {John, who} see_θ v_see:_θ:_pres INFL_v:_3sg

WS 2: {see_θ, {John, who}} v_see:_θ:_pres INFL_v:_3sg

WS 3: {v_see:_θ:_pres:_box(who), {see_θ, {John, who}}} INFL_v:_3sg

WS 4: {{John, who}, {v_see:_θ:_pres:_box(who), {see_θ, {John, who}}}} INFL_v:_3sg

WS 5: {INFL_v:_3sg, {{John, who}, {v_see:_θ:_pres:_box(who), {see_θ, {John, who}}}}}

Initial WS 2: John see_θ v_see:_θ:_pres INFL_v:_3sg C_rel:_who

WS 1: {see_θ, John} v_see:_θ:_pres INFL_v:_3sg C_rel:_who

WS 2: {v_see:_θ:_pres, {see_θ, John}} INFL_v:_3sg C_rel:_who

WS 3: {John, {v_see:_θ:_pres, {see_θ, John}}} INFL_v:_3sg C_rel:_who

WS 4: {INFL_v:_3sg, {John, {v_see:_θ:_pres, {see_θ, John}}}} C_rel:_who